Manchester bomber Salman Abedi's brother will soon go on trial in Libya over his suspected role in the attack.

Libya's chief investigator in the case, Asadiq Al Sour, told the BBC that Hashem Abedi is suspected of having helped his brother in the suicide attack and collected materials for him to execute his fatal plan. He would be presented before a court of law within two months at most, he added.

"All the signs point to Hashem being directly involved and collecting the materials for the suicide bombing that took a lot of innocent lives in Manchester," Sour said.

The development came almost two months after the 20-year-old was arrested in Tripoli. The younger brother of Salman was held soon after the 22 May attack in the foyer of Manchester Arena as crowds were leaving an Ariana Grande concert. The blast had killed at least 22 and injured 59 others.

Earlier, Hashem was also questioned by British police in Tripoli several times. Their father Ramadan, who was also detained in Libya and interrogated, has been released as authorities said they had no concrete evidence against him.

A relative of the Abedis said that Ramadan had been shocked at what his son Salman did.

The 22-year-old, who was born in Manchester to Libyan parents, was seen in Libya more than a month before the bombing. Officials investigating the case said that he spent almost a month in Tripoli before returning to Britain to execute his plan.

Meanwhile, another relative of the brothers — named Mohamed Younis Abedi — has also been taken into custody in eastern Libya. Salman reportedly used his credit card to buy components for the bomb.

Libyan authorities have also given the British police a list with names of people in the UK who they think should be questioned. The people in the list are not necessarily suspects but they could help give vital information and take the case forward, the authorities said.

"These people should be questioned to get more information about the suspects, their movements, their ideologies or if there was any sign they were going to carry out the attack," the prosecutor said.

Manchester arena bomber Salman Abedi
Salman Abedi is seen in this image taken from CCTV on the night he committed the attack in Manchester arena in this handout photo released to Reuters on 27 May 2017 Greater Manchester Police/Handout via Reuters