Sessions said he shares President Trump's "deep concern" about leaked information concerning Monday's suicide bombing in Manchester, England.
In a statement released ahead of a gathering of North Atlantic Treaty Organisation leaders in Brussels, the U.S. president said the leaks were "deeply troubling" and promised to "get to the bottom of this".
Trump pledged to "get to the bottom" of the leaks, calling them "deeply troubling" and asking the Justice Department and other agencies to "launch a complete review of this matter".
President Donald Trump issued a statement Thursday, condemning "leaks of sensitive information" pertaining to the investigation of the terrorist bombing at an Ariana Grande concert in Manchester this week.
The official, who spoke on condition of anonymity because of government rules that bar civil servants from speaking to reporters without prior authorization, wouldn't say which country Abedi had arrived from to Istanbul.
British Prime Minister Theresa May on Thursday said progress was being made in the investigation, but that "the public should remain vigilant". "It damages decades of confidence between the United Kingdom and U.S. services, the cohesion of the "Five Eyes" group, and sharing of information with French, German and other security services", said former reviewer of terrorism legislation Alex Carlile.
It is unclear who the source of the leaked information was.
They added that Manchester has been hosting since years huge communities of Libyan Islamists including a prominent suspect of belonging to al-Qaeda, Abu Anas al-Libi. "And initial searches of premises have revealed items that we believe are very important to the investigation", Hopkins said Thursday.
Turkey's government on Wednesday furnished British authorities with a file on Abedi, a senior Turkish official said.
A minute's silence was held in memory of the victims at 11am around the country, as The Queen flew to Manchester to visit a hospital caring for numerous survivors.
It has emerged that Abedi, the British-born son of Libyan parents, had been banned from a mosque in Manchester after criticising an imam for "talking b******s" during a sermon critical of the so-called Islamic State terror group.
Greater Manchester Police have provided the first full breakdown of the arrests made in the huge investigation to establish whether there was a "network" behind Salman Abedi's suicide attack at Manchester Arena on Monday night.
Authorities indicated he may have been part of a terrorist network intent on carrying out further deadly assaults in and around the Manchester area.
"The sharing of information among people who need to know is absolutely vital", said Ringel, who now works at the Soufan Group security consultancy.
In the Libyan capital Tripoli, Abedi's younger brother, 20-year-old Hashem, and their father, Ramadan, are being held by special forces linked to the interior ministry.
The city's two giant soccer clubs, Manchester United and Manchester City, laid aside their rivalry to jointly donate £1 million (S$1.8 million) to an emergency fund set up to support families affected by the attack.
One of those in custody is believed to be Abedi's elder brother, Ismail, but police have continued to refuse to confirm the fact. Little is known about what Abedi did in those places.
Abedi, whose sister said he "wanted revenge" for Western military strikes in the Middle East, was a "former subject of interest" to MI5, a Whitehall source confirmed.
As the nation mourns, Queen Elizabeth II visited victims and hospital personnel at the Royal Manchester Children's Hospital today. The National Health Service said 75 people had been hospitalized.