Following the arrests made yesterday in Derbyshire and South Yorkshire, warrants of further detention have, this afternoon, been granted to continue questioning the four men in custody.
Detectives from Counter Terrorism Policing North East have been given until 4pm on December 25 to charge, release or apply for a further extension to custody.
As part of continuing activity at the scene in Chesterfield following the arrest of a terrorism suspect yesterday, specialist teams have returned to assist with the ongoing searches.
This is a precautionary measure and officers say they will continue to take every step necessary to prioritise the safety of local residents.
They added that they recognised that local people may have concerns as a result of the activity but asked people to remain 'alert but not alarmed'.
The cordoned off area in the town was significantly reduced yesterday afternoon and is remaining in its current position.
Superintendent Michelle Shooter said: “I would like to thank the people of Chesterfield for their patience and understanding during the unavoidable disruption.
“We’d ask that people are calm, resilient and measured in what they say and how they act during what is a difficult and concerning time for local communities.
“Please remember that, although speculation is natural, it is often wrong.
“We are continuing to support officers from Counter Terrorism Policing North East as the investigation continues.
“Our officers are patrolling the area to offer reassurance to the public.”
Officers have also advised residents to 'act on their instincts' if they see or hear something that could be terrorist related.
People can call the police, in confidence, on 0800 789 321 but - in an emergency - you should always dial 999.