Newspaper headlines: 'MI5 was warned' about attacker
The authorities were warned about Salman Abedi and there were chances to stop him before the Manchester bombing, say many of the papers.
Attention has been drawn on to Abedi's family, the Daily Mirror pictures his brother, Hashem, on its front page after he was detained by militia in Libya and accused of plotting an attack in Tripoli.
Libyan police told the Daily Mail Hashem knew in advance about the bombing and their father had links to a militant group. But the Times says his family was concerned about his radicalisation, and had taken away his passport.
After photos of bloodstained evidence were leaked to the New York Times, the Guardian reports Theresa May will "confront" Donald Trump over the stream of intelligence that has been revealed to the US media.
The Daily Telegraph warns of a growing diplomatic row across the Atlantic with the Sun saying the prime minister is "furious" about the leaks. It says British ministers are "seething" at disclosures that could put potential prosecutions at risk, and that Mrs May will "demand answers" from President Trump when they meet later today.
The Mirror suggests the suspected detonator in the pictures was specially made, and that the bomb was assembled by somebody with a "deep knowledge" of explosives. In agreement, the Times says the battery apparently used in the device is more expensive and powerful than usual, suggesting the maker was determined not to fail.
But why are British people learning crucial details via leaks to US newspapers from American intelligence, asks the Sun, adding: "Is it because they place a much greater value than our police on the public's right to know?"
Writing in the Telegraph, a former State Department official Jeremy Shapiro, says the leaks are a price worth paying for co-operation with the US. He says leaking is nothing new, and is not necessarily malicious, and that for stretched British counter-terrorism teams, access to American intelligence on global networks is "worth the world".
Some of the papers have criticised social media companies for failing to remove videos on how to make a bomb. In an investigation by the Times, detailed guides were found freely available on Facebook and YouTube with users being able to see slickly produced films on how to make the poison, ricin.
The two companies tell the paper they take the problem seriously and remove offending material when they are alerted. But the Sun says it's appalling that a simple search can find such material, and says firms must do more.