The report says two pieces of information came to MI5 indicating possible criminal activity by Abedi, but this wasn't judged to be related to possible terrorist acts.
The head of MI5, Andrew Parker, is believed to have briefed Cabinet ministers about the alleged terror plot on Tuesday.
Naa'imur Zakariyah Rahman, 20, and Mohammed Aqib Imran, 21, were due in court on terror charges on Wednesday.
Scotland Yard, military intelligence security service MI5 and West Midlands Police reportedly had been investigating the plot for "several weeks".
A plot to assassinate UK Prime Minister Theresa May has been foiled, Sky News reported on Tuesday.
United Kingdom authorities think they've arrested two men who plotted to kill Prime Minister Theresa May after "bomb (ing) their way into" her official residence, the Guardian reported.
2 students shot near Washington high school, police say
One of the victims was found in the parking lot by the football field, Troyer said, and one was found in the school's locker room. Deputies are seeking a green sedan with multiple males inside that may have fled the school after the shooting, Troyer said.
Northern Kentucky's General Cable Corp. agrees to be acquired in $3B deal
It expects the deal to lift underlying earnings per share by 10-12 percent within the first year after it is finalised. Massachusetts-based Martingale Asset Limited Partnership has invested 0.02% in General Cable Corporation (NYSE: BGC ).
Taylor Swift Throws "Bomb" Potluck Dinners, According To Tiffany Haddish
Then when I cut them up, I smile. "So when I get over there she got all this food, it was so good", she said. They call it joyful greens.And then [Swift] ate my greens.
Suicide bomber Salman Abedi detonated an explosive at an Ariana Grande concert that killed 22 people on May 22.
A man died in a terrorist incident at Finsbury Park mosque in north London in the same month - and, in September, an attempt to bomb a Tube train at Parsons Green station failed.
Stringent protective measures were first put in place in the 1970s, and were tightened during the 1980s when Irish republicans launched attacks on the British mainland. The device landed in the back garden.
The nearest the IRA got to killing a British prime minister was in 1984 when they targeted the hotel Margaret Thatcher and top officials were staying in for that year's annual Conservative party conference in Brighton on Britain's south coast.