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Global central bank chiefs said they “stand in full solidarity” with Jay Powell, in an unprecedented show of support after US authorities opened a criminal investigation into the Federal Reserve chair.

Central bank governors from 11 institutions on Tuesday issued a statement saying they “stand in full solidarity with the Federal Reserve System and its Chair Jerome H Powell”, who has been the target of repeated attacks by the Trump administration.

“The independence of central banks is a cornerstone of price, financial and economic stability in the interest of the citizens that we serve,” the statement said.

The signatories included European Central Bank president Christine Lagarde, Bank of England governor Andrew Bailey, Bank of Canada chief Tiff Macklem and Pablo Hernández de Cos, the general manager of the Bank for International Settlements (BIS).

Lagarde signed on behalf of the ECB and also the 21 national central banks in the euro area.

US prosecutors have launched a criminal investigation into Powell over a $2.5bn renovation of the Fed’s headquarters, sharply escalating the Trump administration’s attacks on the central bank.

Powell, who has previously played down the tensions with US President Donald Trump, has dismissed the investigation as a pretext aimed at robbing the Fed of its monetary policy independence.

The Fed chair’s term is due to end in May, with a successor yet to be announced by the Trump administration. But Kevin Hassett, director of the National Economic Council and a Trump ally, and Kevin Warsh, who previously served on the Fed board of governors, are widely understood to be the frontrunners.

Trump is facing a growing backlash on Capitol Hill over the Department of Justice probe, even from within his own party. Republican senators, including Thom Tillis of North Carolina and Lisa Murkowski of Alaska, have publicly expressed concern about the risks of jeopardising the Fed’s independence.

Tillis said he would oppose the confirmation of any nominees to the central bank until the matter was resolved, a position that was supported by Murkowski.

The FT reported on Monday that the probe had galvanised Fed officials to resist Trump’s attacks and could push the chair to remain a governor in 2028, according to officials.

John Williams, president of the New York Fed, defended Powell on Monday evening, describing him as “a man of impeccable integrity”.

He also warned that history had shown that when attempts to undermine central bank independence had been successful, it often led to “very unfortunate economic outcomes”.

The other signatories of Tuesday’s letter were the heads of the Swedish, Danish, Swiss, South Korean, Australian and Brazilian central banks. François Villeroy de Galhau, Banque de France chief, signed in his capacity as chair of the BIS board.