TikTok has sued to block the US state of Montana from banning residents from accessing its social media platform.

Monday's lawsuit comes after last week Montana became the first US state to pass a sweeping ban on the Chinese-owned video-sharing platform.

In a statement, TikTok said the ban conflicts with US free speech rights.

TikTok has come under scrutiny from authorities around the world over concerns that data could be passed to the Chinese government.

The lawsuit filed on Monday in the United States District Court for the District of Montana says it is suing to overturn the "unlawful" ban.

"We are challenging Montana's unconstitutional TikTok ban to protect our business and the hundreds of thousands of TikTok users in Montana," a spokesperson said in a statement.

"We believe our legal challenge will prevail based on an exceedingly strong set of precedents and facts."

The TikTok lawsuit argues that the ban violates the constitutional First Amendment right to free speech.

The company's complaint states that the ban was "unconstitutionally shutting down the forum for speech for all speakers on the app".

The ban is due to take effect in January 2024. It will make it illegal for app stores to offer TikTok, but does not ban people who already have TikTok from using it.

Montana, which has a population of just over one million, banned the app on government devices last December.

TikTok says it has 150m American users. Although the app's user base has expanded in recent years, it is still most popular with teenagers and users in their 20s.

However, there are concerns across the US political spectrum that TikTok could be a national security risk.

The social media platform is owned by ByteDance – a Chinese company. ByteDance has repeatedly denied it is controlled by the Chinese government.

The lawsuit also argues that Montana has overstepped its authority by concerning itself with users' data and national security – which is the purview of the federal government.

It says the ban is based on the "unfounded speculation" that China's government could access TikTok data.

Lawyers for Montana's government have previously said that they expected lawsuits, and that they are prepared to defend the ban in courts.

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