TikTok's chief executive says the company will challenge legislation signed into law by US President Joe Biden that could ban the popular video-sharing app in the country.

The US Senate passed the bill by a bipartisan vote on Tuesday and Biden signed the bill on Wednesday. TikTok would be banned if Chinese operator ByteDance does not sell it within 270 days. Biden could extend the deadline for up to 90 days.

TikTok CEO Shou Zi Chew said in a video post, "Make no mistake, this is a ban on TikTok and a ban on you and your voice." He went on to say: "We are confident that we will keep fighting for your rights in the courts. The facts and the Constitution are on our side and we expect to prevail again."

The app is said to have 170 million users in the US.

There have been increasing concerns that the app could pose a security risk as the Chinese government could exploit it to gain information. But some are opposed to a ban, arguing that it would infringe on rights to free expression.