Egyptian security forces in the Sinai were put on high alert Monday after hard-line Islamist groups threatened to launch revenge attacks on Israel.

The Palestinian Ma’an news agency reported that the attack warnings came in response to the killing of Salafi leader Hisham Al-Sa’adani in an Israeli airstrike on Gaza on Saturday.

The Egyptians are concerned that attacks may be launched in border areas with Israel, and may also include assaults on Egyptian security forces. In particular, troops were ordered to be on the alert for booby-trapped vehicles approaching Egyptian security installations.

On Sunday night gunmen car-jacked an Egyptian security forces vehicle in Sinai and the weekend saw a spiraling increase of violence between Israel and the Gaza Strip.

On Saturday a Gaza-based Salafi Muslim group, The Mujaheddin Shura Council of Jerusalem, claimed responsibility for a Grad rocket fired on Friday at the southern Israeli city of Netivot.

Late Saturday night, an Israeli strike in Jabalia in northern Gaza killed al-Sa’adani, one of the founders of the Salafi group. On Sunday afternoon two terrorists were killed in another airstrike on Gaza.

Since August, Egyptian security forces have been battling to regain control of the Sinai Peninsula, which had become a largely unpoliced operating base for terror groups.

The peninsula, returned to Egypt as a demilitarized buffer zone as part of the 1979 Camp David Accords, had been the origin of several terror attacks aimed at Israel over the past year.

In August, terrorists killed 16 Egyptian policemen and stormed the border with Israel in armored vehicles, where they were halted by the IDF. The attack touched off an anti-terror offensive by Egypt which has roiled the peninsula since.