WASHINGTON, July 26 (Reuters) - U.S. President Joe Biden and China's leader Xi Jinping are expected to talk on Thursday, a source familiar with the planning said, amid fresh tensions over Taiwan and Russia's invasion of Ukraine.

White House national security spokesperson John Kirby told reporters on Tuesday that managing economic competition between the two countries would also be a focus of the call.

It will be the fifth call between the leaders, and comes as China has delivered heightened warnings to the Biden administration about a possible visit by U.S. House Speaker Nancy Pelosi to democratically governed Taiwan, which Beijing claims as its territory.

"Everything from the tensions over Taiwan, to the war in Ukraine, as well as how we better manage competition between our two nations, certainly in the economic sphere," Kirby said of the topics to be discussed.

"This is a call that has been scheduled for a long time and there's already a pretty robust agenda of things for these two leaders to talk about," he said.

Under its one-China policy, the United States does not have official diplomatic relations with Taiwan, but is bound by U.S. law to provide the island with the means to defend itself. The White House has been quick to reiterate that stance has not changed despite speculation over a possible trip by Pelosi.

Kirby said that Pelosi is in the line of succession to the presidency and as such, her overseas travel was a matter of U.S. national security. But only she could make decisions about her travel.

"Bellicosity" in rhetoric from Beijing over the potential trip only escalates tensions, he said.

"We find that unhelpful and certainly not in the least bit necessary given the situation," he said.

The administration has been debating whether to lift some tariffs on Chinese goods as a way to boost the U.S. economy, but Kirby said a decision was not expected ahead of the call.

The call comes as the U.S. Congress considers legislation known as the CHIPs act to provide about $52 billion in subsidies for the U.S. semiconductor industry, as well as an investment tax credit for chip plants estimated to be worth $24 billion, which Biden has urged as crucial for competing with China economically.

Biden referred to the planned call with Xi during virtual remarks urging passage of the legislation on Monday, telling reporters, "That's my expectation, but I'll let you know when that gets set up."

The Senate is expected to vote on final passage in coming days and the U.S. House could follow suit as soon as later this week.