Spanish authorities have folied a plot by a suspected member of Eta to blow up a ferry carrying thousands of British tourists.
The Pont-Aven, which sails between Plymouth and Santander and carries 2,400 passengers, as well as 180 crew, was one of three potential targets, according to media reports.
A spokesman for the Spanish interior ministry told the Daily Telegraph newspaper, that the ferry plot was foiled when police arrested a young Eta terrorist at Santander bus station on Tuesday.
Aritz Arginzonic Zubiaurre, 22, was carrying a rucksack containing a Smith & Wesson pistol, a detonator usually used by Eta for car bombs and false identity documents.
Santander is a popular port of entry, especially for British holidaymakers
The UK Foreign Office is advising holidaymakers to be vigilant.