Four of the arrests - three men and a woman - were made in Birmingham on Friday, while another man was stopped at London's Gatwick airport.

"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," senior police officer Marcus Beale said in a statement.

Beale said the arrests had been made following an investigation by local counterterrorism officers, the domestic intelligence service MI5 and international partners, who included Belgian and French authorities. The operation, he said, had taken place to address "any associated threat to the UK following the attacks in Europe."

The four men - aged 40, 59 and two aged 26 - and the 29-year-old woman were held for questioning by counterterrorism detectives. Police also said they were searching several properties in the Birmingham area.

'Pictures of stadium'

According to media reports, Brussels and Paris attacks suspect Mohamed Abrini was spotted in Birmingham last July. French intelligence sources have been quoted as saying that he photographed an unidentified football stadium during that visit.

Abrini, who was arrested in Belgium earlier this month, confessed to taking part in a bomb attack on Brussels airport on March 22. He is also suspected of involvement in the terrorist attacks that rocked Paris in November.

Abdelhamid Abaaoud, the suspected ringleader of the Paris attacks, also visited Birmingham in October, reports said, and had links with several people living there. British Home Secretary Theresa May has declined to comment, citing the need to protect ongoing investigations.

The suicide bombings in Brussels, at the city's Zavantem airport and on a metro train, killed 32 people last month.

In November, terrorists killed 130 people in the bombing and shooting spree in Paris, including a suicide bombing at a soccer stadium. Both attacks were claimed by the "Islamic State" militant group.

rc/kms (AFP, AP, dpa, Reuters)