Islamist militants have launched a series of coordinated attacks on army checkpoints in Egypt's restive Sinai Peninsula, killing dozens of soldiers.

More than 50 servicemen have also been injured at at least six targeted locations south of the town of Sheikh Zuweid, with fighting still raging in some areas.

The Islamic State (Isis) local offshoot has claimed responsibility for the attacks, which is said to have involved some 70 militants who detonated suicide car bombs, abducted an unconfirmed number of servicemen and seizing several military vehicles.

In a Facebook posting the jihadists claimed they assaulted 15 military and police posts across the peninsula, with three "suicide operations".

An officers' club in the city of al-Arish and a police station in Sheikh Zuweid were among the locations attacked.

The number of victims was not immediately clear. Security officials speaking to AP put the death toll at 38, while local press was reporting more than 60 died. As clashes are still ongoing, the number is likely to grow.

Islamist cells have been active in the peninsula since the Egyptian revolution against then president Hosni Mubarak in 2011.

After former army chief Abdel Fattah al-Sisi took power in a military coup backed by street protests, the group stepped up its operations against police and army and pledged alliance to the IS last year.

Earlier this week, Sisi vowed to further crackdown on Islamist movements, after a separate bomb attack killed Egypt's leading prosecutor, Hisham Barakat, in Cairo.

Barakat had led government efforts to repress followers of ousted president Mohamed Morsi and his Muslim Brotherhood movement.