The father of the 22-year-old who police say bombed a concert in Manchester insists that his son is innocent and had been preparing to go on a pilgrimage to Saudi Arabia.

Ramadan Abedi, 51, also known as Abu Ismail, spoke to The Associated Press by phone from the Libyan city of Tripoli.

He confirmed that his other son, Ismail, had been arrested on Tuesday around Manchester by British authorities in the concert attack probe.

"We don't believe in killing innocents. This is not us," the senior Abedi said.

"We aren't the ones who blow up ourselves among innocents. We go to mosques. We recite Koran, but not that."

Authorities say 22 people died and nearly 120 were wounded in the bombing at an Ariana Grande concert

He said last time he spoke to the 22-year-old Salman was five days ago as he was getting ready for a trip to Saudi Arabia to perform Umrah, a smaller pilgrimage to the holy city of Mecca.

"Last time I spoke to him, he sounded normal. There was nothing worrying at all until two days ago (when) I heard the news that they suspect he was the bomber," Mr Abedi, the father of six children, said.

He said Salman visited Libya a month-and-a-half ago and only returned to Manchester after winning a cheap ticket to Umrah.

He said Salman, who was in his second year of studying economics, was planning to return to Libya to spend the holy month of Ramadan with the family.

He denied that his son had ever been to Syria.

The senior Abedi worked as a security officer under dictator Muammar Gaddafi's rule.

In 1993, he fled the oil-rich North African country to Saudi Arabia after he was accused of helping Islamists by tipping them off before police raids.

He denied having ties to any of Libya's militant groups, including the Libya Islamic Fighting Group, which was linked to al Qaeda.

"This is nonsense," he commented, adding that under Gadhafi, "anyone who went to a mosque raised question marks".

After less than a year in Saudi Arabia, Abu Ismail said he fled to the UK, where he sought political asylum and lived there for 25 years.

In 2011, Abedi returned to Libya during the mass uprising that descended into a civil war and ended with Gaddafi's ouster and death.

Libya since then sank into lawlessness, with rebels turning into militias and undermining successive transitional governments.

The elder Abedi has been appointed administrative manager of Tripoli Central Security forces, which answers to the UN-backed government.

"My message to the world is that there are hidden hands that want to tarnish the image of Muslims who live in the west," he said.