Greater Manchester Police have stopped sharing intelligence relating to the Manchester Arena attack with US government agencies after concerns that US intelligence officers are continuing to leak confidential details of the investigation to the American media.
Home Secretary Amber Rudd yesterday warned the US that the "irritating" leaks of information must stop and said she had received assurances from American officials that they would not happen again.
But just hours after Ms Rudd's comments a US newspaper published crime scene photos of the attack apparently passed to them by US intelligence sources.
Meanwhile, Theresa May confirmed she will raise the controversy with Donald Trump when she meets him at a Nato summit in Brussels on Thursday.
"I will make clear to President Trump that intelligence that is shared between our law enforcement agencies must remain secure," she said, speaking from Downing Street.
The Prime Minister also said the threat level will "remain at critical and the public should remain vigilant", after a meeting of the Government's emergency committee Cobra - meaning another attack is still feared to be imminent.
Lord Blair, former chief of the Metropolitan Police, said the "grievous" breach reminded him of US intelligence malpractice after the 7/7 bombings.
"I’m afraid it just reminds me exactly of what happened after 7/7 when the US published a complete picture of the way the bombs in 7/7 had been made up and we had the same protests," he told BBC Radio 4's Today programme.
"It’s a different world in which the US operates in the sense of how they publish things. This is a very grievous breach but I’m afraid it’s the same as before."
A number of details about the Manchester Arena attack appeared in the US media – most notably on networks NBC and CBS – before British police had publicly released them to the UK media.
The initial death tolls, the fact the attack appeared to be a suicide bombing, and the name of the attacker, were all released through US outlets, apparently via leaky US intelligence sources.
Most recently the New York Times newspaper has published photos it says are scene of the Manchester Arena attack, including the remains of a backpack, screws and nuts, and the remnants of a device held by the bomber.
The episode comes just a week after US president Donald Trump defended his right to leak classified intelligence to other countries' leaders. Mr Trump has also criticised leaking from the US intelligence establishment.
Intelligence is shared between Britain, America, Canada, Australia and New Zealand under the UKUSA agreement, the so-called "Five Eyes" programme.
The latest leaks come after Theresa May personally expressed confidence in the US-UK intelligence sharing programme. Questioned about Mr Trump's apparent leaking to the Kremlin, Ms May had said: "We continue to work with the United States and we continue to share intelligence with the United States, as we do with others around the world."
The Associated Press news agency last week reported an official from an unnamed European country saying that they might stop sharing intelligence with Washington due to leaks, and that continuing to do so “could be a risk for our sources”.