A brain wave reader that can detect lies. Miniaturized cameras that sit inside vape pens and disposable coffee cups. Massive video cameras that zoom in more than a kilometer to capture faces and license plates.

At a police conference in Dubai in March, new technologies for the security forces of the future were up for sale. Far from the eyes of the general public, the event provided a rare look at what tools are now available to law enforcement around the world: better and harder-to-detect surveillance, facial recognition software that automatically tracks individuals across cities and computers to break into phones.

Advances in artificial intelligence, drones and facial recognition have created an increasingly global police surveillance business. Israeli hacking software, American investigation tools and Chinese computer vision algorithms can all be bought and mixed together to make a snooping cocktail of startling effectiveness.

Fueled by a surge of spending from Middle Eastern countries such as the United Arab Emirates, the conference’s host and an aggressive adopter of next-generation security technologies, the event pointed to how tools of mass surveillance once believed to be widespread only in China are proliferating. The rising use of the technologies signals an era of policing based as much on software, data and code as officers and weaponry, raising questions about the effects on people’s privacy and how political power is wielded.

“A lot of surveillance could ostensibly be benign or used to improve a city,” said Daragh Murray, a senior lecturer of law at Queen Mary University in London who has studied police use of technology. “But the flip side of the coin is it can give you incredible insight into people’s everyday lives. That can have an unintended chilling effect or be a tool for actual repression.”

The gold rush was evident at a convention center in the heart of downtown Dubai, where uniformed police representatives from around the world browsed drones that could be launched and powered up remotely. Chinese camera makers showed software to identify when crowds gather. American companies like Dell and Cisco had booths offering police services. Cellebrite, an Israeli maker of systems to break into mobile phones, exhibited inside a “government zone” blocked off from the rest of the conference.

Other companies sold facial recognition eyeglasses and sentiment analysis software, in which an algorithm determines a person’s mood from facial expressions. Some products, like a Segway with a rifle mount, pushed the limits of practicality.

“Nowadays, the police force, they don’t think about the guns or weapons that they’re carrying,” said Maj. Gen. Khalid Alrazooqi, the Dubai Police’s general director of A.I. “You’re looking for the tools, the technology.”

With its deep pockets, serious security challenges and autocratic government, the U.A.E., an important American ally in the Middle East, has become a case study in the potential, and risks, of such policing technologies. The tools can help stop crime and terror attacks but can also become an undemocratic buttress of political power.

Under the leadership of Sheikh Mohammed bin Zayed Al Nahyan, often referred to by his initials M.B.Z., U.A.E. authorities have surveilled critics and activists. Amnesty International and other groups have accused the oil-rich country of human rights abuses against adversaries, including using the Pegasus phone spyware made by the NSO Group of Israel. Protests and free expression in the authoritarian monarchy are severely limited, part of what the government has said is an effort to combat Islamic extremism.

One tech firm based in the U.A.E. with ties to the country’s leadership, Presight AI, sells software nearly identical to products that are popular with the Chinese police. At the conference, its software used cameras and A.I. to identify people, store data about their appearance and track their routes as they wandered the event.

A lack of transparency and oversight for the way surveillance technologies are used opens up the potential for abuse, said Marc O. Jones, author of the book “Digital Authoritarianism in the Middle East” and a professor at Hamad Bin Khalifa University in Qatar.

“The region has become so securitized, and under M.B.Z., the U.A.E. has become so focused on security there’s almost this fetishization of technology,” he said.

Cameras are especially prevalent in the U.A.E.’s two largest cities, Dubai and Abu Dhabi. Dubai, which is flashier and more freewheeling, has cameras tucked away in unassuming corners. In Abu Dhabi, the more conservative center of political power, cameras dominate the cityscape. Grey metal towers that support them shaped like T’s and L’s hang over roads at predictable intervals.

General Alrazooqi, the Dubai Police’s A.I. general director, said in an interview that the cameras were part of a yearslong campaign to become a global leader in police technology — even though the city, which has a population of about 3.5 million, is known for low crime. In recent years, Emirati officials visited police departments and companies in China, Europe and the United States for ideas. The consulting companies K.P.M.G. and Gartner were hired to help with the process, the general said. Dubai bought facial recognition systems from Chinese companies including Hikvision and Huawei.

K.P.M.G., Gartner, Huawei and Hikvision declined to comment.

“We pick what is the best practice in each country and to try to perfect and inject it in the system that we have,” General Alrazooqi said. He added that the “Chinese are the best” at computer vision and facial recognition.

The Middle East has become a “petri dish of different actors,” with China, Russia and the United States vying for influence through their technologies, Mr. Jones said. The heavy presence of Chinese technologies — most cameras visible on the streets are Chinese — is a sign of the country’s rising influence in the Gulf.

Dubai’s police run next-generation systems from a sprawling headquarters north of the city’s downtown skyscrapers and malls. One of those systems, a citywide facial recognition program called Oyoon — Arabic for eyes — can pull the identity of anyone passing one of at least 10,000 cameras, linking to a database of images from airport customs and residents’ identification cards. The police have also required businesses to provide video from their security systems to a centralized government database.

“It’s monitoring the whole city from once you enter at the airport to when you leave,” General Alrazooqi said. He said the systems served the police’s “customers” — a catchall term for the public. “People, they are happy about it,” he said.

The technological capabilities were on display in a police command center, where Dubai’s officers could view live camera feeds and the locations of all emergency vehicles on a giant screen.

“With technology and smart cameras, if you committed a crime within a minute I will know which direction” someone is going, said Lt. Col. Bilal Al Tayer, acting director of the command and control center.

One advanced tool was predictive policing software built by engineers from Dubai with machine learning that identifies where thieves might strike next. Officials said its 68 percent accuracy rate doubled that of an older model. Inside some patrol cars, mapping software gives officers specific routes to drive based on crime data.

Another algorithm, built on the records of automobile accidents, predicted the roughly 4,000 most dangerous drivers in Dubai, who will receive reminders via text message to drive carefully. The most-represented category of bad drivers was older Emirati men, followed by older South Asian men. (Nationality is a factor for the algorithm.)

At the Dubai police fair, officials from the U.A.E.’s Ministry of Interior, which oversees state security and has access to all police cameras, demonstrated how, with a tablet, they could scan the irises of conference attendees and pull up information about when they had entered the country, complete with a recent customs photo. Also displayed was a headset that is said to detect when a part of the brain concerning memories is activated, something a ministry official said is useful during interrogations to determine if a suspect is lying.

Walking among the booths at the conference was Lt. Gen. Abdullah Khalifa Al Marri, the Dubai Police’s commander in chief. The new capabilities on display, however intrusive, were a means to achieve a long-elusive, utopian goal of “zero crime,” he said.

“We don’t break the privacy of the people,” he added. “We are just monitoring.”