Madrid - French police have discovered 500 kilograms of explosives which were believed to have been stored by the militant Basque separatist group ETA, Spanish police sources said Monday.

The explosives were found in a garage in the south-eastern French city of Grenoble on Sunday.

The owner of the garage became suspicious after the people who had rented the garage were not heard of for months, and informed police, the sources said.

Police searched the garage, finding explosives, materials for making bombs and the anagram of ETA.

ETA, which has killed more than 820 people in its campaign for a Basque state created out of northern Spain and southern France, has a large part of its infrastructure based in France. (dpa)