LONDON (AP) — Five people have been arrested in Britain and several properties were searched Friday in Birmingham in an investigation that security officials say is possibly linked to a key suspect in the deadly attacks in Paris and Brussels.

West Midlands Assistant Chief Constable Marcus Beale said the five arrests aimed to address “any associated threat to the U.K. following the attacks in Europe.” The move comes only days after authorities in Belgium detained a suspect in connection with deadly attacks in Brussels and Paris who had ties to the Birmingham area.

Four people — three men aged 26, 40 and 59 and one 29-year-old woman — were arrested Thursday in the central English city of Birmingham and a 26-year-old man was arrested Friday at London’s Gatwick Airport. Police said the five were arrested for suspected ties to the commission, preparation or instigation of acts of terror.

Police would not elaborate on the searches in Birmingham.

A week ago, Belgian authorities arrested and identified the “man in the hat” spotted on video alongside the two suicide bombers who attacked Brussels Airport on March 22, killing 16 people. The suspect, Mohamed Abrini, was also wanted in the Nov. 13 Paris attacks that left 130 people dead.

One European security official told The Associated Press that Abrini had made multiple trips to Birmingham last year, meeting with several men suspected of terrorist activity. The official spoke on condition of anonymity because he was not authorized to provide details about the investigation.

Surveillance had been taking place on suspected cell members in the Birmingham area since the Paris attacks, the official said.

A second European security with access to Belgian counterterrorism data said West Midlands police had closed in on a ring of suspects linked to Abrini’s phone after his recent arrest.

A Belgian judge on Thursday ordered Abrini and six other suspects arrested in connection with the attacks in Paris and Brussels kept behind bars for another month.

Britain has faced multiple terror attacks and plots since four suicide bombers struck London’s subways and buses in 2005, killing 52 people and the four bombers.

Some 800 British citizens have gone to Syria to fight. Of those, about 100 are thought to have died and 300 or so have returned, according to the European security official who spoke about the arrests in Birmingham.

“It would be exceedingly difficult to replicate the scale of the attacks in Paris, as it is still difficult in Britain to access guns and ammunition,” said Shiraz Maher, senior research fellow at the International Centre for the Study of Radicalisation. “However, as we’ve seen from the 2005 suicide attacks, the threat is still severe to Britain.”

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Danica Kirka contributed from London.

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