A New York court in 2012 awarded families billions of dollars of damages against al Qaeda, the Taliban and many Iranian state organisations for their roles in the attacks. The Taliban had hosted Osama bin Laden while the 9/11 attacks were plotted.

The US Justice Department has been negotiating with lawyers for the families about a potential deal to divide up the money if the government supports their attempt to seize it.

Fiona Havlish, whose husband worked on the 101st floor of the South Tower, and Ellen Saracini, whose husband was a pilot of one of the hijacked planes, have called on Joe Biden to help them.

“After our husbands were killed in the September 11, 2001 terrorist attacks, we have spent many years fighting to achieve justice on their behalf,” they said in a statement.

“Together with the others in our case, we obtained an enforceable money judgment against the Taliban and now call on President Biden to ensure the funds we have attached go to us and not the terrorists who played a role in taking the lives of our loved ones.”

Any decision to hand the money over would incense the Taliban, who two weeks ago wrote an open letter to Congress appealing for the funds to be unfrozen.