Police have been given until Christmas Day to decide if they want to charge four men held as part of an operation to foil a suspected attack on 25 December.
Following police raids on Tuesday morning, the men, aged 31, 22, 36 and 41, have been held for questioning.
Detectives have been given till 4pm on Christmas Day to either charge, release or apply for a further extension to custody.
South Yorkshire Police said specialist teams continued to assist with ongoing searches at the scene in Sheffield Road, Chesterfield, Derbyshire, as a "precautionary measure".
A statement called on the public to "remain alert but not alarmed" following a raid on the Mermaid Tradition Fish Bar.
The arrests on Tuesday come after a mosque and community centre in Burngreave, Sheffield, was sealed off, with residents reportedly being woken up at 6am by loud bangs and armed officers wearing camouflage.
Superintendent Michelle Shooter of Derbyshire Police 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.
"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."
South Yorkshire Police Assistant Chief Constable David Hartley said there would be an increased police presence over the holidays.
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"I'd like to thank everyone for their support and patience over the last 24 hours, which has understandably caused some concern within our communities," he said.
"We are continuing to support the investigation and as planned throughout the festive period you will see an increased visibility of both unarmed and armed patrols right across the county."