Five people from Birmingham have been arrested as part of an international anti-terror inquiry in the wake of the Paris and Brussels attacks.
Three men aged 26, 40 and 59 and a 29-year-old woman were detained in Birmingham on Thursday night.
A 26-year-old man was arrested at Gatwick Airport in the early hours of Friday.
West Midlands Police said that the arrests of five suspects in the UK formed part of an extensive investigation into "any associated threat" to Britain following terrorist attacks in Paris and Brussels.
It is believed that these are the first arrests in the UK connected with the investigation into the attacks in Brussels and Paris.
The arrests were made five months after the November 13 attacks in Paris, which left 130 people dead.
The news comes as recordings from inside the Bataclan concert hall, in Paris, reveal what was said between victims and the attackers.
Assistant Chief Constable Marcus Beale, of West Midlands Police, said a number of properties in Birmingham were being searched after the pre-planned and "intelligence-led" arrests.
He said: "This action forms part of an extensive investigation by West Midlands Counter Terrorism Unit, together with the wider counter terrorism network, MI5 and international partners including Belgian and French authorities to address any associated threat to the UK following the attacks in Europe.
"There was no risk to the public at any time and there is no information to suggest an attack in the UK was being planned."
All five people arrested were held on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism.
West Midlands Police has previously refused to confirm reports that images of landmarks in Birmingham, including a shopping mall, were found on a mobile phone belonging to a ring-leader involved in the Paris atrocities.
For the first time, investigators have released what was said during the mass murders, which left 89 people dead at the concert hall.
In the recording, a victim can be heard asking: "Is this a dream, or what?"
Sky News reports that a person can be heard pleading with police not to enter the building "or else they’ll blow everything up".
An attacker says on the recording: "You have bombed our brothers in Syria and in Iraq. Why are we here? We’ve come back from as far as Syria, to do the same to you.
"We are men and we will attack you from the ground. We don’t need jets. You elected your President Hollande, and that was his campaign. You have him to thank for this."
More than 30 people died and 270 were injured when three explosions went off across Belgium’s capital last month.
So-called Islamic State claimed responsibility for the attacks at Brussels Airport and Maalbeek Metro Station.