British police are appealing for information from anyone who saw Salman Abedi carrying a blue suitcase after releasing CCTV footage of the Manchester suicide bomber with the luggage on the day of the attack.

Counter-terrorism officers are working to trace Abedi’s movements in the days before he detonated an improvised explosive outside an Ariana Grande concert killing 22 people and injuring 116 others.

“We continue to track the final movements of Salman Abedi and are particularly interested in his whereabouts between 18 and 22 May 2017,” Detective Chief Superintendent Russ Jackson of the North West Counter Terrorism Unit said in a statement.

“We believe Abedi was in possession of this case in the days before the attack at Manchester Arena on Monday 22 May,” he said.

Police are scouring some 12,960 hours of CCTV recordings in their search for clues, have collected more than 630 pieces of evidence and searched 21 addresses.

Abedi is known to have visited the Wilmslow Road area of Manchester and the city centre with the suitcase, police said.

Attack at Manchester Arena update: image released of Abedi carrying a suitcase. Did you see him? https://t.co/NiBYb83cwj pic.twitter.com/0MK24mvtlO

— Greater Manchester Police (@gmpolice) May 29, 2017

“I want to stress that this is a different item than the one he used in the attack,” Superintendent Jackson said. 

“We have no reason to believe the case and its contents contain anything dangerous, but would ask people to be cautious.”

Superintendent Jackson advised members of the public not to approach the case if they see it, but contact police immediately.

Police are searching a landfill site on the outskirts of Greater Manchester as they hunt the suitcase, the BBC reported.

There have previously been searches in Manchester, Chester and Shoreham-by-Sea in West Sussex, where a 23-year-old man was arrested early Tuesday (AEST) in relation to the bombing.

A total of 14 men have been arrested in England in relation to the May 22 bombing outside an Ariana Grande concert, which killed 22 people and injured 116 others.

National Health authorities told the BBC that 52 people injured in the attack were still being treated in hospital – including 19 in critical care.

It has emerged that British security service MI5 was alerted to Abedi’s attitudes three times prior to the bombing.

MI5 says it will hold an inquiry into the way it handled the warnings that Abedi was a potential threat.

A UK government official had previously been quoted by the BBC as saying Abedi was one of a “pool” of former subjects of interest whose risk remained “subject to review” by the security service and its partners.

Police and security officials have released very little information about the network believed to be behind Abedi, a Manchester-born former university student whose parents had moved to Britain from Libya.

Abedi’s elder brother Ismail reportedly is among the suspects being held in Britain, while his younger brother and father have been detained in Libya.

Authorities believe Salman Abedi returned to Britain from Libya on May 18, and likely completed assembling his bomb at a rented apartment in central Manchester.

CCTV footage

BBC obtained CCTV footage of a man captured the day before the attack.

The footage shows a man, believed to be Abedi, spending five minutes in the store. He purchased tuna, almonds, cleaning products and air freshener.

Shop manager Michael Jones told BBC the man looked “exactly like the guy they’re saying has done the bombings”.

“It’s the same guy that’s been in the shop several times in the past,” he said.

“His eyes stand out so much from the guy that we recognise from the past … It makes me feel quite scared really.”

Grande’s tribute

Singer Ariana Grande’s mother, who was earlier hailed a hero for helping to usher young fans to safety after the explosion, released a statement on Twitter expressing her sadness for the people who lost their lives at her daughter’s concert.

#MemorialDay pic.twitter.com/oUDmB7VD6x

— Joan Grande (@joangrande) May 29, 2017

– With agencies