The developments came hours after the Home Secretary said members of Abedi's circle could still be at large, despite a wave of arrests leading to the country's terror threat level being de-escalated.
Authorities in Libya have detained Abedi´s brother and father, while British investigators appealed to the public late Saturday for details of the bomber´s movements in the days before the attack, which has been claimed by the Islamic State group.
The UK's terror threat level had been lowered to "severe" from "critical" yesterday as a result of the arrests, which means an attack is still highly likely if not imminent.
"But I would not rush to conclusions, as you seem to be, that they have somehow missed something". The Army troops deployed as a result of Operation Temperer will be reduced from Monday night.
Manchester-born Abedi likely received some ISIS training in Syria in the months before the attack, according to information gathered in the preliminary investigation, a U.S. official told CNN on Thursday.
"Until the operation is complete, we can't be entirely sure that it is closed".
"What we are doing is challenging the people who are delivering end-to-end encryption to work with us so that we have a way of keeping people safe", she said.
UK: Manchester Attack Investigation Still at 'Full Tilt'
United Kingdom officials were " furious " when photos appearing to show debris from the attack appeared in the New York Times . But she urged Britons to remain vigilant and said soldiers would remain at high-profile sites throughout the holiday weekend.
The government is facing criticism after acknowledging that Abedi was on security services' radar, but wasn't a major focus of scrutiny. "Every time I've been outside my flat there's someone there or a group of them sitting outside in a vehicle".
Meanwhile, police believe they have made a significant breakthrough in their investigation.
The UK police have identified Salman Abedi as the individual they suspect of having perpetrated the attack and are now investigating the extremist network related to the man.
As officers left the Moss Side area, a handwritten sign appeared on the smashed front door of the property, reading: "This is what the police has caused and we have nothing to do with what happened in the bombing attack".
They said the investigation - which was "making good progress" - had around 1000 people working on it and hundreds more officers involved in security across Greater Manchester.
Abedi's city centre flat was one of the last places he went - and where he may have made the final touches to his explosive device - before going to the arena, police have said.