Anti-terror police are on the hunt for a blue suitcase Salman Abedi was carrying on the day of the deadly Manchester bombing as raids on properties continue.
The public are being asked to contact the police immediately if they see the piece of luggage, which officers have no reason to believe contains anything dangerous but are asking people to be cautious.
Greater Manchester Police has released an image of the suicide bomber with the hip-high case in the city centre on May 22.
Detective Chief Superintendent Russ Jackson from the North West Counter Terrorism Unit said: "Did you see Abedi with this suitcase between the 18 and 22 May 2017? Where did you see him with it during that time?
"You may have seen him in the Wilmslow Road area or Manchester city centre with the suitcase or know where the suitcase has been. If you have any details about the suitcase we need you to get in touch and let us know.
"We believe Abedi was in possession of this case in the days before the attack at Manchester Arena on Monday 22 May. I want to stress that this is a different item than the one he used in the attack.
"This image was taken from CCTV in the city centre on 22 May."
Mr Jackson continued: "The public should not approach the case if they see it but contact police immediately on 999."
Police raided more homes on Monday as the relentless search for the network behind the suicide bombing continued a week on from the attack.
Officers executed a warrant at an address in Rusholme and the search remains ongoing, GMP said on Monday evening.
Police activity also centred around a tip beside the M66 motorway, between Bury and Heywood, and officers stood on guard at the entrance to the Viridor site and also at a public footpath around it.
One worker in a fluorescent orange coat could be seen beside a man in a white boiler suit inspecting waste close to a large digger which was sifting through material.
Viridor confirmed its Pilsworth site was being searched, and the company is assisting police.
Early morning raids were carried out at a house in Manchester, along with searches carried out in Chester and Shoreham-by-Sea, on the south coast of England.
A 23-year-old was held in the small seaside town on suspicion of terror offences in the early hours of Monday morning, GMP said.
As the police operation continued, more questions were being raised about possible security and intelligence blunders surrounding what was known about bomber Salman Abedi.
With the massive operation to dismantle his terror network showing little sign of slowing, 14 men were being held in custody in connection with the attack.
Police have been working round the clock since Abedi killed 22 people, seven of them children, and injured more than 100 last Monday night in the worst terrorist atrocity since the July 7 bombings in 2005.
A total of 16 arrests have been made in connection with the attack, although two people have since been released.
The suspect held in Shoreham was arrested after police entered a flat above a parade of shops in Brunswick Road in the town centre.
It is not the first time the area has been linked to terror.
The Deghayes family, of Saltdean, have lost three sons killed fighting in Syria, while a fourth son has also travelled to the country to fight the Assad regime.
Relation Omar Deghayes was held by the United States as an enemy combatant at Guantanamo Bay detention camp between 2002 and 2007 after he was arrested in Pakistan.
In Manchester, police raided the home of another Libyan family in the Whalley Range area of south Manchester on Monday morning, with searches of the property continuing.
It has been reported that MI5 has launched two urgent inquiries into whether it missed the danger posed by Abedi, amid allegations it was warned of his deadly intent.
The domestic security service is said to be investigating whether any glaring errors were made in the handling of intelligence before the attack.
Spy chiefs are believed to have held an emergency review in the days after the atrocity, while a separate in-depth inquiry is being conducted to look at the decision making surrounding his case before the massacre, the Guardian reports.
A senior Whitehall source previously has said Abedi was a "former subject of interest" to the security services whose risk "remained subject to review".
In the wake of the attack, it emerged British counter-terror authorities were grappling with 500 investigations into 3,000 individuals.
Security sources later confirmed to the Press Association that a further 20,000 individuals were said to have been considered ''subjects of interest'' in the past, meaning as many as 23,000 people have appeared on the radar of counter-terror agencies, although the period the figures cover is unclear.