Egyptian F-16 jets struck Islamic State group militants in the Sinai Peninsula where dozens were killed in attacks and ongoing clashes on Wednesday, security officials and a witness said.

Security officials said the fighter jets bombarded IS positions in the town of Sheikh Zuweid, where the militants had taken up positions on rooftops and mined streets leading to the police station.

An unprecedented wave of IS attacks on Egyptian soldiers in the Sinai Peninsula on Wednesday killed at least 36 people, mostly troops, with the toll expected to rise, officials said.

The dead included several civilians, according to security and medical officials, who said 38 militants were also killed as they battled soldiers and policemen in the North Sinai town of Sheikh Zuweid.

An army spokesman said 70 militants took part in the attacks, firing RPGs at several checkpoints and that the army had killed 22 militants.

Reports on the death toll have varied - according to a security source speaking to private daily Al-Shorouk, the number of troops killed was much higher, as many as 64 soldiers. Al-Ahram newspaper reported on its website that at least 20 people had been killed in ongoing attacks and gun battles.

IS-affiliated militant group Wilayat Sina' (Sinai Provice) said it had raided 15 checkpoints and an officers' club using suicide bombers and mortar shells.

North Sinai Governor Abdel Fattah Hrhor declared a state of emergency in the province as Israel sealed off its border crossings with Egypt.

The attacks in N. Sinai seem to be heading towards an open battle rather than a hit&run. In some positions, militants are advancing #Egypt — Ibrahim Halawi (@Ibrahimhalawi) July 1, 2015

At around 10am, massive explosions and gunfire erupted in the Sheikh Zuweid area, reportedly the result of a suicide truck bomb, according to Youm7.

An Apache helicopter was hit by a militant missile and was forced to withdraw from the battlefield, according to Al-Masrsad Al-Sinawi, a Sinai-based news outlet.

The assault comes two days after the country's state prosecutor Hisham Barakat was killed in a Cairo bombing targeting his convoy.

Barakat was the most senior government official killed since militants launched an insurgency following the military's overthrow of Islamist president Mohamed Morsi in 2013.

Reports indicate this was planned & coordinated assault. Suicide bombers hit checkpoints, RPGs stationed on roof tops & element of surprise — Joel Gulhane - چويل (@jgulhane) July 1, 2015

The authorities designated Morsi's Muslim Brotherhood a "terrorist group" in December 2013 as part of a crackdown on the opposition that has left hundreds of his supporters dead and thousands in jail.

Egypt’s North Sinai has witnessed a wave of attacks since the ousting of Morsi in July 2013. Most of the attacks, which have killed hundreds of security personnel, have occurred in North Sinai.

On Tuesday, two children were killed when a rocket reportedly fired by militants struck their home.