Trump condemns leaks after UK police stop sharing attack information

British Prime Minister Theresa May said earlier she would tell Trump that intelligence shared between their two countries had to remain secure, in a rare public show of dissatisfaction with Britain's closest security ally.

"The alleged leaks coming out of government agencies are deeply troubling," Trump said in a statement released after he arrived in Brussels for a NATO summit, also attended by May.

"I am asking the Department of Justice and other relevant agencies to launch a complete review of this matter, and if appropriate, the culprit should be prosecuted to the fullest extent of the law."

Salman Abedi, a 22-year-old British-born man with Libyan parents, blew himself up on Monday night at the Manchester Arena indoor venue after a concert by U.S. singer Ariana Grande, whose fans are mostly children and teenagers.

The explosion killed 22 people, ranging from an eight-year-old schoolgirl to parents who had come to pick up their children.

With the official threat level raised to "critical", meaning a further attack could be imminent, troops have been deployed to free up police, and armed officers patrolled trains for the first time in Britain.

Police, who believe Abedi was part of a network, are holding eight people in custody in connection with the attack.

"I want to reassure people that the arrests that we have made are significant, and initial searches of premises have revealed items that we believe are very important to the investigation," Manchester's police chief Ian Hopkins said.

Abedi had recently returned from Libya, where his father and younger brother were arrested by a militia on Wednesday.

Abedi passed through Istanbul on his way to Europe, Turkish security officials told Reuters, but said they had no records of him entering Syria during his travels as had been suggested on Wednesday by the French interior minister.

A source with knowledge of the investigation told Reuters Abedi might have made the bomb himself or with some assistance from an accomplice. That was a change from previous thinking that a bomb-maker might be at large.

"The focus is still the search for accomplices and the network but he could have made this bomb himself," the source said.

Over the past three, days several key details of the investigation, including the name of the bomber, first came out in U.S. media, angering British police who feared such leaks risked compromising their investigation.

"I will make clear to President Trump that intelligence that is shared between our law enforcement agencies must remain secure," May said before departing for the NATO summit.

The decision to stop sharing police information with U.S. agencies was an extraordinary step for Britain, which is usually at pains to emphasise its "special relationship" with the United States.

"This is until such time as we have assurances that no further unauthorised disclosures will occur," said a counter-terrorism source, who spoke on condition of anonymity.

British authorities did not say that the investigation had in fact been compromised by the leaks.

The attack injured 116 people, of whom 75 were admitted to hospital and 23 remain in a very serious condition, health authorities said.

Queen Elizabeth visited the Royal Manchester Children's Hospital, where some of the casualties have been treated, and was filmed chatting with a girl lying injured on a ward.

A minute's silence was observed in honour of the victims at a square in central Manchester, after which crowds broke into an emotional chorus of "Don't Look Back in Anger", an old hit song by the band Oasis who are from the city.

The city's two giant soccer clubs, Manchester United and Manchester City, laid aside their rivalry to jointly donate 1 million pounds ($1.3 million) to an emergency fund set up to support families affected by the attack. They labelled their initiative "A City United".

The bombing has caused revulsion across the world for targeting children and teenagers. Former U.S. President Barack Obama, meeting German Chancellor Angela Merkel at an event in Berlin, said the pair were "heartbroken", while Trump told fellow NATO leaders the attack was "savage" and "barbaric".

Many European cities, including Paris, Berlin and Brussels, have suffered attacks in the past two years, underlining the importance of confidential intelligence cooperation.

Britain routinely shares intelligence with the United States bilaterally, and also as part of the "Five Eyes" network which also includes Australia, Canada and New Zealand.

Trump was widely criticised this month after it emerged he had discussed sensitive Syria-related intelligence, originating from an ally, with Russian officials at a White House meeting. May said at the time Britain would continue to share information with Washington.

Pictures published by the New York Times included remains of the bomb and of the rucksack carried by the suicide bomber, and showed blood stains amid the wreckage.

"I think it's pretty disgusting," said Scott Lightfoot, a Manchester resident, speaking outside a train station in the city. He criticised media for publishing such material.

"Who's leaking it? Where's it coming from? This is British intelligence at the end of the day, people shouldn't be finding out about this."

In a statement, the New York Times defended its decision to publish the images, saying they were "neither graphic nor disrespectful of victims".