Egyptian helicopters have launched a fresh assault on armed groups in the Sinai region, as Egypt's military confirmed that Friday's air raid that killed four fighters was carried out by one of its planes.

There were unconfirmed reports of casualties in the latest assault on Saturday, which happened when Apache helicopters hit areas south of Sheikh Zuwaid in north Sinai, reported by Egyptian state media.

A witness told Al Jazeera that the armed fighters responded by firing towards the helicopters.

The armed group, Ansar Beit al-Maqdis, had earlier said Israeli drones were behind the attack that killed four of their fighters on Friday. It accused the Egyptian army of co-ordinating the attack with the Israelis.

A funeral was held for the fighters on Saturday, with the bodies of the four driven through several border towns in Sinai.

Dozens of men on pick-up trucks flying their black flag paraded through the towns, in an act of defiance to the army, witnesses said.

"Our heroes became martyrs during their jihadi duties against the Jews in a rocket attack on occupied lands," Ansar Bayt al-Maqdis said on its website.

Fresh assault

Hours later, Egyptian military helicopters targeted fighters in a fresh assault near the village of Touma in north Sinai, according to witnesses.

Colonel Ahmed Aly, the military spokesman, said in a written statement that the military "surveilled and dealt with a group of terrorists" involved in past attacks in the peninsula.

Fighters based mainly in north Sinai near Israel's border have escalated attacks on security forces and other targets since July 3, when the army ousted president Mohamed Morsi and installed a new regime in Cairo.

But the army has been reluctant to confront the fighters inside towns in order not to provoke the tight-knit tribes, military sources said.

There had been conflicting reports about the source of Friday's attack.

Egypt and Israel have co-operated in tackling armed groups in Sinai in the past. The Egyptian army said on Wednesday it had killed 60 fighters in the Sinai Peninsula in the month since Mohamed Morsi was deposed as president.

PHOTO CAPTION

A funeral convoy carring the bodies of the fighters through the Sinai region

A-Jazeera