Beñat Atorrasagasti Ordóñez, an alleged member of the Basque separatist group ETA, who is believed to have gone on the run in 2001, has been arrested in Edinburgh.
Lothian and Borders Police arrested Atorrasagasti in a raid on Friday night in the Leith area more than 10 years after he went on the run.
Spain's Interior Ministry said he had rented property there for "some time".
It says that Atorrasagasti, originally from San Sebastián, was a "carrier" for Eta, taking people and materials across the border between Spain and France.
He is believed to have escaped authorities in 2001 and fled to France.
In 2008 he was sentenced in his absence by the Paris Correctional Court to five years in prison.
Atorrasagasti was reported to be on Spain's "most wanted" list since 2008, according to the Scotland on Sunday newspaper.
Spanish officials requested his arrest, following an investigation which began several months ago.
A spokesman for Lothian and Borders Police said: "A 36-year-old man has been arrested in Edinburgh on two European warrants, in connection with historical crimes committed in Spain and France.
"We can confirm that no armed officers were involved and at no time was any member of the public at risk. The man will appear at Edinburgh Sheriff Court on Monday under the terms of the Extradition Act."