A US federal appeals court has rejected a legal challenge by TikTok to a law designed to ban the social media platform in the US.

Under the law enacted in April, the video-sharing app would be banned if its China-based parent company ByteDance does not sell it by January 19. Concerns about information leaks to China are behind the legislation.

In the ruling on Friday, the court upheld the law, rebuffing the arguments from the TikTok side that it violates the rights to free expression and is unconstitutional.

The court ruled that it withstood constitutional scrutiny. It said the law is for the government to protect free speech from "a foreign adversary nation" and to "limit that adversary's ability to gather data" on US people.

TikTok expressed its intention to appeal to the Supreme Court in a statement issued on Friday after the ruling. It said, "The Supreme Court has an established historical record of protecting Americans' right to free speech, and we expect they will do just that on this important constitutional issue."