Spanish police arrested 13 people in the northern city of Bilbao on Wednesday who are suspected of financing Islamist militants in Algeria, the Interior Ministry said.
A ministry statement said police had broken up a gang of 12 Algerians and one Iraqi, suspected of involvement in robbery, drug trafficking and receiving stolen goods.
"The arrests have come about due to common crime and an investigation is under way into whether some of the proceeds were channelled into financing international terrorism," Interior Minister Alfredo Perez Rubalcaba said in parliament.
Police had confiscated stolen passports, stolen gold and silver objects, 7,500 euros ($10,230) in cash and receipts for money orders to Algeria, amongst other items.
Media reports said those arrested were suspected of links with al Qaeda in the Islamic Maghreb, the North African wing of Osama bin Laden's network. Al Qaeda has spoken of recovering territories in Spain -- known as Al Andalus -- which were under Muslim rule for centuries.
Islamist militants killed 191 people with bombs planted on Madrid trains on March 11, 2004, and police have subsequently broken up several other alleged terrorist plots.