Counter-terrorism officials have launched an investigation into a possible new Islamist plot to attack Britain after four men were arrested in northern England.

The army’s bomb disposal unit was called to a house in Chesterfield, Derbyshire, after a 31-year-old man was arrested there early on Tuesday, while neighbours were evacuated from their homes. The other men, aged 22, 36 and 41, were arrested at three separate properties in Sheffield.

The arrests followed a joint operation by police and MI5. They made their move having decided it was too risky to allow the suspects to remain free. This was based on intelligence, which can be wrong, rather than evidence, which police say they are now trying to obtain.

Investigators believe whoever was behind the alleged plot may have had materials related to the making of improvised explosive devices, as well as the knowhow to construct them.

There have been concerns that there could be an attack over the Christmas and new year period. The MI5 director general, Andrew Parker, and police chiefs have warned in recent months that the terrorist threat is at an unprecedented level, with 10 plots believed to have been disrupted since March, including one allegedly targeting Downing Street.

The men arrested on Tuesday are being questioned at a police station in West Yorkshire and are suspected of having Islamist links.

All four were arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism under section 41 of the Terrorism Act 2000.

Supt Una Jennings, of South Yorkshire police, said: “I understand our local communities will have concerns about this morning’s police activity but I want to offer my reassurance that we will continue to serve and protect the public.

“We work very closely with our colleagues at the north-east counter-terrorism unit [Nectu] and we will ensure we maintain these strong links in order to provide a high level of service and delivery to everyone in our community. Public safety is our utmost concern.”

Residents in Sheffield reported hearing loud bangs in the early hours, which a Nectu spokeswoman confirmed was caused by counter-terrorism officers as they gained access to the properties where arrests were made.

The area around the Chesterfield property attended by the army bomb squad was evacuated and cordoned off while a search was conducted.

One resident, Jake Fox, 24, said he had been asked to leave his home on a street near the raided property. “The police told us to go to Chesterfield stadium,” he said. “They wouldn’t give us any information.”

His brother Simon, 22, said: “We have seen army, police from all over, we have seen a couple of packages being removed by the bomb disposal unit.”

Another address was being searched in Stocksbridge, Sheffield, in connection with the arrests, police said.

The owner of Stocksbridge Gents Barbers confirmed his shop had been raided as part of the operation. Mohammed Ojaky, who opened the business in May, said he believed police may have targeted the wrong address.

“The person they were looking for may have worked at the shop before I took it over or was connected to a member of staff,” he said. “Police took a copy of the CCTV and a list of names of staff members.”

The Fatima community centre in the Burngreave area of Sheffield was sealed off, with police vehicles parked outside and police tape across the entrance.

The centre’s volunteer manager, Amar Ghaman, said there was nothing “strange going on here and nothing for the Muslim community to worry about”.

Ghaman said two men had offered to rent a flat attached to the back of the building around three months ago. He said he did not know the men but their “papers were clean”.

“We and everyone at the centre condemn terrorism completely and we do not associate ourselves with that,” Ghaman added.



The UK threat level for terrorism remains at severe, meaning an attack is deemed highly likely.