Four of the arrests -- three men aged 26, 40 and 59 and a 29-year-old woman -- were in Birmingham in central England on Thursday, while a 26-year-old man was arrested at London Gatwick Airport.
Five people have been arrested for alleged terror offences in Britain -- including one man stopped at an airport -- in an investigation involving French and Belgian authorities, police said on Friday.
Four of the arrests -- three men aged 26, 40 and 59 and a 29-year-old woman -- were in Birmingham in central England on Thursday, while a 26-year-old man was arrested at London Gatwick Airport on Friday.
"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," senior police officer Marcus Beale said in a statement.
"The arrests were pre-planned and intelligence-led... 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," Beale said, adding that police were searching a number of properties in Birmingham.
The Daily Telegraph newspaper quoted government ministry sources as saying that the arrests were "significant".
Contacted by AFP, a police spokeswoman declined to comment further including on any possible link to attacks in Belgium last month and in France in November in which a total of 162 people were killed.
Belgium's federal prosecutor's office also declined to give further details on the investigation.
"The federal prosecution office wishes to emphasise the good collaboration with the British authorities," it said.
Top Brussels and Paris attacks suspect Mohamed Abrini, who was arrested in Belgium earlier this month, was spotted in Birmingham last July, according to reports.
Abrini has confessed to being the "man in the hat" caught on video with suicide bombers at Brussels airport on March 22 shortly before they detonated their devices.
Abrini is charged with "terrorist murders".
He is also linked to the Paris massacre after being caught on video at a motorway gas station with top suspect Salah Abdeslam, who is now awaiting extradition from Belgium to France.
The Wall Street Journal newspaper cited unnamed Western officials last year saying several people with connections to the Paris attacks' suspected planner Abdelhamid Abaaoud live in the Birmingham area.
Suicide bombings at Brussels' airport and on a metro train killed 32 people last month, while jihadists killed 130 people in a bombing and shooting spree in Paris in November.
Both attacks were claimed by the ISIS group.