EL-ARISH, Egypt (Ma'an) -- Egyptian authorities on Saturday seized 2.5 tonnes of explosives hidden in three trucks en-route to the Sinai peninsula.

The trucks contained different types of explosive materials and mortar devices, Egyptian sources said, which were hidden in tires within the vehicles.

Four suspects confessed to trying to smuggle the explosives into Sinai, the sources added.

Egyptian security forces have waged a security campaign in the desert Sinai region to reign in militant groups, after 16 Egyptian border guards were killed in an attack on their post in August.

On Friday, an Egyptian army officer was shot dead by snipers in the city of El-Arish, while earlier this week Egyptian military forces foiled an attempted car-bombing near a Sinai military base.