Washington DC - US President Donald Trump and his administration are studying whether dismissing independent Federal Reserve chief Jerome Powell is an option, his top White House economic aide said Friday.

"The president and his team will continue to study that matter," National Economic Council director Kevin Hassett told reporters when asked if firing the central bank chief was a possibility, one day after Trump lashed out at him.

The US president does not have direct authority to fire Federal Reserve governors, but Trump could initiate a lengthy process to attempt to unseat Powell by proving there was "cause" to do so.

Trump has frequently criticized the Fed chairman, whom he originally nominated during his first term, accusing Powell of playing politics.

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Powell had warned Wednesday that Trump's sweeping tariffs would likely push up prices and constrain economic growth, and could put the Fed in the unenviable position of having to choose between tackling inflation and unemployment.

On Thursday, the Republican president insisted that he could force Powell out.

"I'm not happy with him. I let him know it and if I want him out, he'll be out of there real fast, believe me," Trump said.