A fifth man has been arrested over an alleged terror attack plot, police said.

Two buildings in Sheffield are being searched by counter-terrorist officers after the 21-year-old from the city was held late on Friday.

It follows the arrests of four men in the South Yorkshire city and nearby Chesterfield in Derbyshire on December 19.

Anti-terror police are searching two properties in Sheffield in relation to the latest terror probe

Police were seen searching a house in the Fir Vale area of Bristol earlier this afternoon

Officers secured the boundary before a full forensic search could begin

A spokesman for Counter Terrorism Policing North East (CTPNE) 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 intelligence-led arrest was made in the Firth Park area of Sheffield at approximately 11pm on Friday evening.

'Two addresses, a residential address in Fir Vale and a business address in Firth Park, are currently being searched by officers.'

Cordons remained outside as they searched the house he shared with 'a few' people who neighbours described as 'very private'.

Terraced Hampton Road in the Fir Vale area of Sheffield, South Yorks., was sealed off following the man's arrest at about 11pm last night (December 29).

Neigbours reported seeing police forensics officers enter the property late last night after one of the house's occupants opened the door to arresting officers.

Mishair Nasir, 34, said: 'It was about 11pm last night.

'We saw 7-8 police cars pull up then a guy with shoulder-length hair opened the door and the police went in.

'We saw one older guy try and leave but police told him to stay inside.

'My husband's a taxi driver and I was really worried there was a bomb so I told my him to come home from work.'

Mrs Nasir's husband Elhadi, 40, said: 'There are too many different people living there so you don't know who is living there.

'But they don't cause any problems.

'It's very scary - my wife was really worried and couldn't sleep.'

Another neighbour who did not want to be named said: 'The first I knew about it was hearing banging last night.

'Then we saw police and an ambulance - at first I thought there had been a murder.

'It's really scary though because you just don't know who's living next door.

'There're all from different countries and don't speak the same language as me.'

South Yorkshire police said they wanted to reassure the public following the recent upsurge in terror raids in the Sheffield area

Two of the men arrested on December 19 – Chesterfield fish and chip shop owner Andy Star, 31, and Farhad Salah, 22, from Sheffield – have been charged with one count of engaging in the preparation of an act of terrorism.

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

They allegedly planned to build an IED that would be placed inside a driverless car, with a laptop controlling the vehicle and detonating the device.

A 36-year-old man from Burngreave in Sheffield also remains in custody, while a 41-year-old from Meersbrook in Sheffield was released on Saturday, police said.

South Yorkshire Police Deputy Chief Constable Mark Roberts said: 'I understand that this activity will cause concern, especially as there has been similar activity in recent weeks.

'I would like to firmly reiterate that we continue to work closely with our colleagues in Counter Terrorism Policing North East to keep our communities safe and identify threat and risk.

'Our main priority is public safety and protecting the people of South Yorkshire.

'If you have any concerns around any suspicious activity, I would encourage you to please call police in confidence on 0800 789321. In an emergency always dial 999.'