An Egyptian soldier has been killed and two security officers injured in an attack on a military checkpoint in Egypt's North Sinai, state news agency MENA reported.

Unknown assailants fired a rocket-propelled grenade at an armoured vehicle stationed at the checkpoint on a road leading to Al-Arish international airport on Monday.

Egypt's military has been battling an Islamist militant insurgency in the Sinai Peninsula which has spiked since the army overthrew Islamist president Mohamed Morsi on 3 July amid mass nationwide protests against his rule.

The army has killed around 100 militants during an offensive to "purge [the Sinai Peninsula] of terrorism." 

On Sunday, Egypt's military said it had seized arms caches in the peninsula, including machineguns and mortars.

The army said nine militants were killed on Saturday in an air and ground offensive in North Sinai. Nine other suspects were arrested and three caches of weapons were destroyed.