By David Shepardson

WASHINGTON (Reuters) -Five TikTok users, who also create content posted on the short-video app, filed suit in U.S. District Court in Montana late Wednesday seeking to block the state's new ban on the Chinese-owned platform.

Montana Governor Greg Gianforte on Wednesday signed legislation to ban TikTok in the state, effective Jan. 1. The five users seek to block the law, which makes it unlawful for the app stores of Alphabet Inc's Google and Apple Inc to offer TikTok within the state.

The video app is used by more than 150 million Americans.

The lawsuit names Montana Attorney General Austin Knudsen. The TikTok users argue the state seeks to "exercise powers over national security that Montana does not have and to ban speech Montana may not suppress." The suit adds users believe the law violates their First Amendment rights.

Knudsen did not immediately comment.

"Montana can no more ban its residents from viewing or posting to TikTok than it could ban the Wall Street Journal because of who owns it or the ideas it publishes," the lawsuit said.

The suit is assigned to Judge Donald Molloy, who was nominated to the bench by President Bill Clinton, a Democrat, in 1995.

TikTok, owned by Chinese tech company ByteDance, said Montana's ban "infringes on the First Amendment rights of the people of Montana by unlawfully banning TikTok," and said it will "continue working to defend the rights of our users inside and outside of Montana."

TikTok has faced growing calls from U.S. lawmakers and state officials to ban the app nationwide over concerns about potential Chinese government influence over the platform.

Gianforte, a Republican, said the bill will further "our shared priority to protect Montanans from Chinese Communist Party surveillance."

TikTok has repeatedly denied that it has ever shared data with the Chinese government and has said the company would not do so if asked.

Montana, which has a population of just over 1 million people, said TikTok could face fines for each violation and additional fines of $10,000 per day if it violates the ban.

The American Civil Liberties Union (ACLU) slammed the law as "unconstitutional."

An attempt by former President Donald Trump to ban new downloads of TikTok and WeChat through a Commerce Department order in 2020 was blocked by multiple courts and never took effect.

(Reporting by David Shepardson; Editing by Leslie Adler and Anna Driver)