US President Donald Trump has called for the chair of the Federal Reserve to quit "immediately", in an escalation of his attacks on Jerome Powell.

"'Too Late' should resign immediately!!!", Trump said in a post on his Truth Social platform.

He also included a link to a news article about a US federal housing regulator calling for Mr Powell to be investigated over his testimony about renovations to the central bank's Washington headquarters.

Trump nominated Mr Powell to be the Fed chair during his first term. Since then, he has repeatedly criticised him for not cutting interest rates, but it's unclear whether the president has the authority to remove him from the post.

Despite the president's continued criticism of Mr Powell, he said earlier this year that he had "no intention of firing him".

Trump wants the Federal Reserve to lower interest rates to help boost economic growth.

Mr Powell said on Tuesday that the Fed would have cut rates already had it not been for the impact of Trump's tariff policies.

When asked during a meeting of central bankers in Portugal whether US rates would have been cut again this year if the administration had not announced its plan to sharply increase tariffs on countries around the world, Mr Powell responded, "I think that's right."

The US Federal Reserve declined to comment about Trump's remarks when contacted by the BBC.

Ahead of Trump's return to the White House at the start of this year, Mr Powell said he would not step down if the president asked him to and that it is "not permitted under law" for the White House to force him out.

Board members of independent federal agencies like the Federal Reserve can only be forced out before their terms expire "for cause," according to a landmark US Supreme Court ruling in 1935.

However, Trump has often challenged political norms, including firing some independent regulators, actions that have been contested in court.

On Wednesday, Federal Housing Finance Agency director Bill Pulte, who has previously strongly criticised Mr Powell, called for him to be investigated.

"I am asking Congress to investigate Chairman Jerome Powell, his political bias, and his deceptive Senate testimony, which is enough to be removed 'for cause,'" he posted on X.

Last week, Mr Powell told the Senate that reports about soaring costs and expensive features at the Fed's headquarters were "misleading and inaccurate in many, many respects."