Two suspected members of the Basque separatist group are now under arrest as the police seize one of the biggest explosives caches ever in Spain. Let's take a closer look.

Police on Tuesday found over 800 kilos of explosive material on a family farm of two suspected members of the Basque separatist group ETA, now under arrest.

The uncovered explosives cache is one of the biggest ever in Spain.

The raid raises fears that ETA may be planning an attack despite declaring a cease-fire.

Police raided the farm of ETA suspects brothers Igor and Aitor Esnaola after they were detained in northern Spain on Tuesday.

They seized bomb-making material, including 850 kilograms of ammonium nitrate fertilizer, 13.5 kilograms of the explosive pentrite and detonators when they raided the farm house near the town of Legorreta, in Gipuzkoa.

The arrest of the Esnaola brothers came a day after French police detained another pair of suspected ETA members in France after a checkpoint shootout and overnight sweep by hundreds of police and helicopters in the Creuse region of central France on Monday.

ETA has killed more than 850 people in half a century of struggle for an independent Basque state in northern Spain and southwest France.

But the separatist group has been weakened by a string of arrests and discoveries of arms caches in Spain, France and Portugal.

The separatists declared a permanent ceasefire on January 10.

This was rejected by the Spanish government as insufficient because it did not come with full disarmament.