AN Israeli helicopter gunship killed an Islamic Jihad leader and his deputy after the militant group took responsibility for a suicide bombing which killed five Israelis.

Shadi Mohanna, who leads the armed wing of the organisation in northern Gaza, and his deputy, Mohammed Razaina, died when a rocket blasted their car in the Jebaliya refugee camp near Gaza City overnight.

Israeli warplanes also launched a series of bombing raids in northern Gaza.

Palestinian security officials said Israeli fighter jets had bombed three areas of northern Gaza, targeting open fields used by militants to fire rockets into southern Israel.

There were no reports of any casualties in the airstrikes, which the army said was aimed at rocket-launching sites used by militants.

Witnesses in the area said they saw militants from Islamic Jihad firing at least two missiles into southern Israel in response to the earlier airstrike which killed two militants from the movement's armed wing, the Al Quds Brigades.

The strikes were the latest round of violence in a series of actions that appear to have ended a period of relative peace that's ruled Gaza since Israel removed its settlements two months ago.

Israel and Islamic Jihad have traded rapid blows since Sunday, when another Islamic Jihad leader was killed during an Israeli military operation.

Islamic Jihad responded to that attack with the suicide bombing in the Israeli city of Hadera on Wednesday; Israel retaliated with the attack on Mohanna.

The Israelis have accused Mohanna of firing rockets from Gaza into Israeli communities as well as attacking Israeli soldiers.

There were conflicting accounts of how many people were killed in yesterday's attack.

Israeli military spokesmen said four Islamic Jihad members were in the car, and that after the strike, the car rolled over and a crowd gathered.

The car then exploded, injuring three bystanders.

Palestinian reports said five people had died.

The attack came after the Israeli Cabinet approved increased military operations against Islamic Jihad, including assassinations, air artillery strikes and the possible use of large-scale ground forces in the West Bank and the recently evacuated Gaza Strip.