The United States would come to Taiwan's defense and has a commitment to defend the island China claims as its own, US President Joe Biden said on Thursday, though the White House said later there was no change in policy towards the island.

"Yes, we have a commitment to do that," Biden said at a CNN town hall when asked if the United States would come to the defense of Taiwan, which has complained of mounting military and political pressure from Beijing to accept Chinese sovereignty.

While Washington is required by law to provide Taiwan with the means to defend itself, it has long followed a policy of "strategic ambiguity" on whether it would intervene militarily to protect Taiwan in the event of a Chinese attack.

In August, a Biden administration official said US policy on Taiwan had not changed after the president appeared to suggest the United States would defend the island if it were attacked.

A White House spokesperson said Biden at his town hall was not announcing any change in US policy and "there is no change in our policy," but declined further comment when asked if Biden had misspoken.

"The US defense relationship with Taiwan is guided by the Taiwan Relations Act. We will uphold our commitment under the Act, we will continue to support Taiwan's self-defense, and we will continue to oppose any unilateral changes to the status quo," the spokesperson said.