The Egyptian military says its air force has killed 19 Islamic extremists in the volatile Sinai Peninsula.

It says in a statement Thursday that the strikes in northern and central Sinai on "terrorist strongholds" of the local Islamic State group affiliate also destroyed four vehicles.

The announcement comes two days after police said they killed one of the militants involved in an attack on a checkpoint that killed a policeman near south Sinai's famed Saint Catherine's Monastery earlier this week.

The military claims to kill hundreds of militants in the area each year, although it rarely offers proof and journalists and non-residents are banned from the area. Hundreds of security forces have been killed.

The IS-led insurgency is centered in northern Sinai, but militants have occasionally struck farther south.