Updated May 25, 2017 22:11:06

Photo: This image reportedly shows Abedi carrying the backpack he allegedly used in the bombing (Supplied: Sky)

British police have arrested two more men in connection with the Manchester bombing, as local media have broadcast photos of what they say is suspect Salman Abedi walking through the city centre wearing the backpack he used to carry his explosives.

UK broadcaster Sky News aired two screengrabs of security camera footage, reporting that British police believed they showed Abedi walking in Manchester's Arndale shopping centre late on Friday.

The Arndale Centre is a short walk from the Manchester Arena, the scene of the attack which killed 22 people on Monday night (local time).

The man seen in the images is carrying a blue backpack on his back, with a sales tag still hanging off it.

British police believe Abedi withdrew 250 British pounds ($430) from an ATM before he went shopping in the centre around 7:00pm (local time), according to Sky.

Photo: The backpack had its sales tag hanging off it. (Supplied: Sky)

Sky reported that police believed that the backpack was used in the Manchester Arena bombing.

At the same time, the New York Times published photos which it said came from the scene of the bombing. Some of the photos showed remnants of blue material from what appeared to be a Karrimor-branded backpack.

Abedi, a 22-year-old British citizen born to Libyan parents, died in the attack, which targeted fans leaving a concert by US pop star Ariana Grande.

Twenty-two people, mainly young fans, were killed, with dozens more injured.

UK police have arrested eight people in the aftermath of the bombing, with Home Secretary Amber Rudd saying Abedi "likely" did not act alone.

Abedi's father and brother were also arrested by authorities in Libya.

Libyan counter-terrorist officers in Tripoli arrested Salman Abedi's brother, 18-year-old Hashim Abedi, and said the teenager had confessed that both he and his brother were a part of the Islamic State (IS) group.

Photo: Hashim Abedi, the younger brother of the Manchester bomber, has been arrested. (Facebook: Yousef Hannaa)

But the father, Ramadan Abedi, denied his son's involvement in an interview with The Associated Press before being arrested, saying they did not "believe in killing innocents" and he believed "hidden hands" were behind the attack.

Great Manchester Chief Constable Ian Hopkins said on Thursday they had made significant arrests and had uncovered important items as part of the investigation.

He said eight people were being held in custody, while a woman was released without charge.

"I want to reassure people that the arrests that we have made are significant, and initial searches of premises have revealed items that we believe are very important to the investigation," Chief Constable Hopkins told reporters.

"These searches will take several days to complete."

As yet none of those held in the UK have been charged.

As authorities hunt a possible terrorist cell, ABC's Philip Williams says questions will no doubt be asked about how authorities missed this deadly attack.

The British investigation is now reportedly focusing on who helped Abedi, and on whether the bomb-maker is still at large.

Chief Constable Hopkins declined to comment on whether police had found the alleged maker of the explosive device, but the BBC reported that security services thought the bomb was too sophisticated for Abedi to have built by himself.

But British police have stopped sharing information with US authorities, after earlier warning their efforts were being hampered by continuing leaks to US media, the BBC has reported.

Meanwhile the first deployments of thousands of soldiers have taken place, with troops standing guard over possible targets in London and other cities after British PM Theresa May yesterday raised the country's terror threat level to 'critical'.

Soldiers were seen at the Houses of Parliament, Ms May's Downing Street residence and at the London police headquarters at New Scotland Yard.

In Manchester, British army bomb disposal experts were called in to investigate a reported suspicious package which was later deemed safe, police said Thursday, adding that a cordon had been removed.

"There was a cordon in Hulme, not Trafford as previously suggested, relating to a possible suspicious package," Greater Manchester Police said in a statement.

"This has now been deemed safe and the cordon has been removed."

Photo: Soldiers have been deployed on the streets of London after the threat level was raised. (Reuters: Toby Melville)

ABC/wires

Topics: law-crime-and-justice, terrorism, unrest-conflict-and-war, united-kingdom, england

First posted May 25, 2017 12:25:29