TikTok is facing its first ban by a US state over national security concerns after Montana’s governor signed a bill prohibiting downloads of the social media app, setting up a potential legal fight over free speech.

The bill, signed by Governor Greg Gianforte on Wednesday and taking effect in January, bans TikTok from operating within Montana and prohibits app stores from allowing downloads of the app, which is owned by Chinese company ByteDance. If they do not comply, TikTok and the app stores, such as Apple and Google, could face fines of $10,000 per violation per day, according to the new law.

The statewide ban, which has been strongly opposed by free-speech advocates, comes amid mounting security concerns from governments and regulators around the world about the company’s ties to Beijing via its Chinese parent. Earlier this year, the US government called for a ban or divestiture of the short-form video app, fearing it could harvest data on its 150mn American users for Chinese espionage purposes.