"If we were to stop pooling our resources, especially on hard targets like ISIS, Russia and North Korea, all of us would be less safe, and the prime minister and President Trump both know that".

Acquaintances were stunned to learn that Salman had carried out the suicide bombing but there were signs that he was troubled, friends and officials said Wednesday.

British media indicated a 23-year-old man arrested Tuesday is likely to be Abedi's older brother Ismael.

"This is not us", the 51-year-old Abedi said in a telephone interview from Tripoli.

Before his arrest in Tripoli yesterday, Abedi's father said his son had been affected by the death.

It comes as British authorities work to uncover the "network" behind the deadly attack, with six men in custody in England and Libya with fears a second attack may be imminent.

He had claimed his son seemed "normal" when they spoke five days ago and insisted: "We don't believe in killing innocents". "The military are continuing to support the police under Operation Temperer -- 1,000 members of the military are assisting in that", said Rudd.

In recent years, after his parents moved back to Libya, Abedi began failing out of college and expressing more radicalized ideas. She said he had been known to security forces "up to a point".

Ahmed bin Salem, a spokesman for the Special Deterrent Force (SDF), the paramilitary group that is questioning the family, told the Associated Press that Salman "was giving farewell" when he phoned. Abedi often complained that the British were "unjust to the Arabs".

He said the Libyan community in Manchester wanted to do all it could to help and was collecting money for the victims of the bombing.

Muslim men attend Friday prayers at Manchester Central Mosque following the terror attack in the city earlier this week.

Based on the account from a younger brother, investigators think Abedi used the internet to learn how to make a bomb and "seek victory for the Islamic State", bin Salem said.

That teenager, Abdulwahab Hafidah, was stabbed in the neck in what local media reports called retaliation for his having gone into rival gang territory.

US Secretary of State Rex Tillerson met United Kingdom foreign secretary Boris Johnson in London today and said the US took "full responsibility" for the leaks.

"No government can prevent every terrorist attack".

"He had the same ideology as his brother".

The British government also declined to comment on whether or not the United Kingdom requested the pair's arrest by the Libyan authorities. On Wednesday, soldiers were seen on the streets of London, including arriving at the Houses of Parliament, where just two months ago, a terrorist drove a vehicle through pedestrians and stabbed to death an unarmed police officer.

The attack on Manchester bore similarities to other recent attacks in the West in terms of choice of venue (these included the Bataclan concert hall in Paris and the Pulse nightclub in Orlando Florida) as well as timing (the attack on Paris just days before the country went to the polls).

Earlier today, a man was arrested in connection with the suicide attack at the concert by American actress-singer Ariana Grande at Manchester Arena on Monday night.

In April, six Syrian soliders and nine civilians, including four children, were killed following a U.S. strike on a chemical weapons store.

Opponents accused Corbyn of politicising the Manchester attack.