The Federal Reserve governor Lisa Cook will sue the Trump administration over its bid to fire her over unconfirmed allegations of mortgage fraud, her attorney has said.

Donald Trump announced he was firing Cook on Monday night, in an extraordinary move that marks the latest escalation in the US president’s attack on the central bank’s independence.

But Trump has “no authority” to remove her from the Fed’s board of governors, Abbe Lowell, Cook’s attorney, argued in a statement to reporters, saying: “His attempt to fire her, based solely on a referral letter, lacks any factual or legal basis. We will be filing a lawsuit challenging this illegal action.”