A key government adviser on terrorism has called on Staffordshire's most senior police officer to apologise to four men arrested at a county hospital.
Police cordoned off part of the hospital grounds
Police detained the men under the Terrorism Act at Stafford General Hospital but found no evidence of any crime before releasing them.
Lord Carlile said the chief constable of Staffordshire should apologise and an independent inquiry should be held.
Police are to meet members of the mens' families on Monday.
A force spokesman said it would be reviewing Lord Carlile's comments.
On BBC Radio 4's World Tonight, he said: "People should not be arrested under the Terrorism Act unless there is a real terrorism issue."
He continued: "The police have a wide range of powers enabling them to arrest people for suspicion of crime or suspicion of illegal immigration."
He thought the Independent Police Complaints Commission should take a close look at the incident.
"The most important thing is if there has been an error, then there should be fence-mending at once and it may have to start with an apology," he said.
Officers arrested the men, aged 24 to 30, on Wednesday after hospital staff became concerned about the illness of a fifth man.
Searches of four houses in Stafford found nothing which was a cause for concern, said police.
Assistant Chief Constable Suzette Davenport said at the time of the men's release: "Our inquiries have revealed no links with any incident of terrorism or any other type of crime.
"Throughout their detention the men were fully co-operative and we are grateful to them for their help and understanding."
Staffordshire Police said an independent advisory group had been set up for feedback from communities in the town following the arrests.
The arrests were made under the Terrorism Act 2000.