Egyptian army forces have killed 83 militants as part of a security campaign in the restive Sinai Peninsula, according to a military spokesman on Monday.

In a statement, Colonel Tamer al-Refai said 77 militants have also been arrested in northern and central Sinai in the period between Sept. 28 to Nov. 4.

He added that three troops were killed and injured in clashes with militants, but without giving any further details.

According to the spokesman, two underground tunnels and 14 hideouts used by militants had been destroyed and 4,707 illegal immigrants arrested as part of the operation.

The Sinai Peninsula has remained the epicenter of a militant insurgency since 2013, when the army ousted Mohamed Morsi — Egypt’s first freely elected president — in a military coup. Morsi died in June during a trial session on “espionage” charges.

The Egyptian military has launched a major operation early last year to hunt down Daesh-linked militants based in the peninsula.