A brother of the Manchester bomber knew of his plans and has been arrested in Libya, according to the country's security forces.

Salman Abedi's father has also been arrested in capital Tripoli, counter-terror police in the North African country said.

Hashem Abedi was held on Tuesday evening and is claimed to have known about his elder brother's plot to detonate a nail bomb at the end of a pop concert on Monday night.

Twenty-two people were killed in the attack following an Ariana Grande show at Manchester Arena.

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A spokesman for Libya's counter-terror force said: "We have evidence that he is involved in Daesh (Islamic State) with his brother.

"We have been following him for more than one month and a half. He was in contact with his brother and he knew about the attack."

Seven people have been arrested in the UK in relation to the atrocity, including Salman's other brother, 23-year-old Ismail Abedi.

Hashem Abedi, 20, is suspected of planning to carry out an attack in Tripoli and travelled from London to the Libyan capital on April 16, the spokesman added.

Libyan authorities have claimed Hashem was receiving money transferred by Salman, 22, at the time of his arrest.

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There was no reason given for the arrest of father Ramadan Abedi, who was detained outside his home in a Tripoli suburb on Wednesday afternoon.

Earlier on Wednesday, Ramadan had insisted his son Salman was innocent.

He said: "We don't believe in killing innocents. This is not us."

Ramadan and his wife emigrated to London to escape Libya's former dictator Muammar Gaddafi before moving to south Manchester.

They are believed to have returned to their home country following the overthrowing of Gaddafi in 2011, with their son Salman remaining in the UK.

Sky News has revealed how Salman had links to an IS cell which operated in Manchester and knew one of the terror group's most prolific recruiters.

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The developments in Libya come amid the arrest of seven people in the UK in connection to the atrocity in Manchester.

Greater Manchester Police say they are investigating a "network" over the suicide bombing carried out by British-born Salman.

On Wednesday evening, a man was arrested following a search at a property in Nuneaton, Warwickshire, and a woman was arrested following an armed raid on a block of flats in Blackley, north Manchester.

A man was arrested in Wigan a few hours before, with officers assessing a package he was carrying.

Earlier on Wednesday, three men were arrested after police executed warrants in south Manchester.

Greater Manchester Police chief constable Ian Hopkins said: "It's very clear that this is a network that we are investigating."

Ismail Abedi was arrested on Tuesday, at a supermarket near to a house occupied by his brother.

Officers also entered an address in Manchester city centre on Wednesday afternoon and carried out a controlled explosion.

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Following Monday's attack, the UK terror level has been raised to critical, the highest possible, meaning an attack is expected imminently.

Nearly 1,000 soldiers are on patrol, supporting police at key locations.

Army personnel are replacing armed police at sites including Buckingham Palace, Downing Street and the Palace of Westminster as part of Operation Temperer.

Wednesday's Changing of the Guard at Buckingham Palace was cancelled to redeploy police officers, while all public tours and events in Parliament have been cancelled.

A minute's silence will be held at 11am on Thursday to remember those who lost their lives or were affected by the attack.

Police have now identified all 22 victims, with those who died including an eight-year-old girl and an off-duty female police officer.