Salman Abedi's younger brother arrested in Libya over alleged Isis links

Security forces say Hashem Abedi was planning an attack in the capital, Tripoli

Salman Abedi, who is believed to have killed 22 people in an attack. His brother has been arrested in Libya (Handout)

Hashem Abedi, the younger brother of Manchester attacker Salman Abedi, has been arrested in Tripoli, Libya.

He was planning a "terrorist act" in the city, Libyan authorities have said.

A local counter terror force known as Rada detained Mr Abedi, 20, on Tuesday evening.

His brother Salman killed 22 people and injured many more after detonating a suicide bomb at a concert in Manchester on Monday night.

Hashem Abedi had been in touch with attacker Salman Abedi, spokesman Ahmed Bin Salem told Reuters.

"We have evidence that he is involved in Daesh (Isis) with his brother," Mr Bin Salem said. 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."

Salman Abedi is also believed to have spent time in Libya, from where his family originates, prior to the attack.

The north African country is highly unstable and home to numerous militias and factions, including Isis and other Islamist extremists.

Another sibling, Ismail Abedi, 23, was arrested yesterday in Manchester by UK counter-terror officers.

The Abedi parents are living in Libya and have reportedly denied their son's involvement in the attack.

Ramadan Abedi told the AP he spoke with his son, Salman, less than a week ago and that he sounded "normal".

Five people in total have been arrested in the UK in connection with the bombing.

In the UK, the investigation into the bombing is continuing and the government has placed the threat level at 'critical'.

Armed troops are patrolling the streets in support of the police around sensitive sites.