A fifth man has been arrested as part of an investigation into a possible Islamist plot to attack Britain, police have said.

Counter-terror officers arrested a 21-year-old man in Sheffield on Friday evening on suspicion of preparing acts of terror, and two buildings are being searched in the north of the city in connection with the alleged plot.

Police said the intelligence-led arrest was made in the Firth Park area at approximately 11:00pm. A residential address in Fir Vale and a business address in Firth Park are being examined.

The raids follow the arrests of four men in Sheffield and nearby Chesterfield before Christmas.

Two of the men arrested on 19 December – Andy Sami Star, 31, who owns a fish and chip shop in Chesterfield, and Farhad Salah, 22, from Sheffield – have been charged with one count of engaging in the preparation of an act of terrorism under section 5 of the Terrorism Act 2006.

The men, both Iraqi Kurds, are due to appear at the Old Bailey in London on 19 January.

A 36-year-old man from Burngreave in Sheffield also remains in custody. A 41-year-old from Meersbrook in Sheffield was released without charge on Saturday.

A spokesman for Counter Terrorism Policing North East said: “The 21-year-old man, from the Fir Vale area of Sheffield, was arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism under Section 41 of the Terrorism Act 2000.

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