US President Donald Trump's administration is preparing to print a new $250 bill that could feature his portrait, if lawmakers allow it.

Federal law bars printing US money featuring the image of a living person, but Trump allies in Congress have introduced legislation to make an exception.

A Treasury Department spokesperson told the BBC the agency "is conducting appropriate planning and due diligence" in response to the legislation.

The lawmakers behind it said the bill amount would symbolise the country's 250th anniversary this year. If approved, it will be the latest example by Trump and his allies to put his face, name, and likeness on national institutions and symbols.

Artistic concepts of the $250 bill have not been publicly released, but designs have been requested by the Bureau of Engraving and Printing (BEP), a sub-agency of the Treasury that develops and produces US currency. The Washington Post first reported the Treasury Department's plans.

"Should this legislative mandate be signed into law, the BEP is moving proactively to produce a $250 commemorative note which will appropriately recognise the 250th Anniversary of our great nation," the Treasury spokesperson said in a statement.

Trump's signature is already set to appear on US paper notes as part of the nation's semiquincentennial celebrations.

The new legislation was introduced last year by US House Representative Joe Wilson, a Republican from South Carolina. It would need approval from both the US House and Senate.

When asked about a possible new bill during a White House briefing on Thursday, Treasury Secretary Scott Bessent said "it's all in the hands" of Congress and that, while his department was preparing in case the legislation passes, the Treasury would follow the law.

He also said he did not "think there's anything untoward" about including an image of the person in office on a bill marking the country's 250th anniversary.

The move to create the $250 note could also break with a different federal law that specifies the denominations that can be produced. That law doesn't include $250.

US Senator Mark Warner, who sits on the Senate Banking Committee, criticised the plans.

"As Americans struggle with the rising cost of gas, groceries, housing, and health care, President Trump's priorities for taxpayer dollars are completely detached from the challenges families face every day," Warner, a Democrat from Virginia, said in a statement.

"If this White House put even half as much energy into working to lower costs as it does into stoking the president's ego, American families wouldn't need that new $250 bill just to fill up their gas tanks."

The $100 bill, featuring Benjamin Franklin, one of the US founding fathers, is the largest bill printed today. The US has previously issued larger notes including $500, $1000 and $10,000 notes but these were discontinued in 1969. They remain legal tender but not in circulation, as they are largely kept by private currency collectors.

New currency notes typically take years to develop and involve a range of agencies including the Federal Reserve Board and the US Secret Service. The designs are also held in secret.

"Note designs are typically made public six to eight months ahead of time for global public education and cash handler education purposes," according to the BEP. "To do so earlier would aid counterfeiters and cause confusion in the marketplace, lowering confidence in U.S. currency."

It is unclear if the notes could be printed in time for the 250th anniversary on 4 July.

Since taking office last year, Trump and his allies have worked to put his face, name, and likeness on public buildings and US symbols.

The Kennedy Centre was renamed to include Trump's name, and his portrait will feature on US passports. The presidential jet Air Force One is also being repainted in Trump's preferred colours.