But in the US, politicians were openly briefing the media on what they had been told about Abedi and his "cell of Isis-inspired terrorists".

Theresa May is expected to raise UK concerns when she meets Donald Trump on Thursday.

The row - which goes to the heart of the close intelligence-sharing relationship between the transatlantic allies - provides an awkward backdrop to the Prime Minister's meeting with President Trump at the Nato summit in Brussels.

A Whitehall source said: "We are furious. This is completely unacceptable.

"These images leaked from inside the US system will be distressing for victims, their families and the wider public.

"The issue is being raised at every relevant level by the British authorities with their US counterparts."