ATHENS (Reuters) - Greek and British police said on Monday they had broken up a criminal network that supplied forged travel documents to hundreds of illegal migrants trying to reach Britain and northern European countries.

The gang supplied more than a thousand lost or stolen passports and travel documents that were procured from accomplices in Barcelona, Spain, in the past six months.

Police swooped on the gang last week, arresting 24 suspects in Greece and nine in Britain.

One of the alleged Barcelona accomplices is a 28-year-old Algerian suspected of militant ties who had been under police surveillance, the semi-official Athens News Agency reported. A police spokesman in Greece said the Algerian national was one of 12 people wanted for questioning.

“This is a blow to organized crime,” said Christos Papazafiris, head of the security directorate at Hellenic Police, describing an operation that involved intelligence sharing between Greek and British security officials.

More than 1,000 passports or travel documents are thought to have been smuggled from Spain to Greece in the past six months, he said.

Speaking at the same news conference, Chris Hogben of the British National Crime Agency said the criminal network had provided travel documents to “hundreds of Iranian nationals” seeking to reach the UK through Turkey, Greece and other European countries.

More than one million refugees and migrants have passed through Greece since early 2015, but tens of thousands are still stranded in camps across the country after border shutdowns throughout the Balkans thwarted their journeys.

The suspected Algerian accomplice dispatched the passports and travel documents to Greece from Spain via courier services.

Theodoros Chronopoulos, a police spokesman, said the forged documents were sold to individuals trying to leave Greece, Spain and France by air for countries including the United Kingdom, Germany, the Netherlands, Belgium and Switzerland.

The passports exchanged hands for between 3,000 euros($3,184.50) and 15,000 euros each.