Spain's civil guard said today it had found a car containing explosives on the southern tip of its border with Portugal.
A local media source said the civil guard found 100 kilograms (220 lbs) of explosives as well as detonators, although a military police spokesman refused to confirm the quantity.
The find in Ayamonte, 200 kilometres west of Seville, comes just over two weeks after the Basque separatist Eta organisation formally called off a 14-month-old ceasefire.
That truce had effectively been broken by a bomb attack at Madrid airport in which two people were killed.
Spain's socialist government had attempted peace talks with ETA last year but called them off after the airport bomb.
ETA have killed more than 800 people in four decades of struggle for the independence of Basque territories in northern Spain and southern France.