GAZA CITY, Palestinian Territories: Gaza's Hamas rulers on Tuesday launched a month-long campaign urging alleged Palestinian "collaborators" with Israel to turn themselves in return for leniency.

"We announce the opening of the door to repentance for remaining collaborators and for all those who have fallen into the traps set by the enemy's intelligence services," interior ministry spokesman Islam Shahwan told reporters.

"We urge them to return to the bosom of their people and their families," he said, noting that the offer of clemency was open until April 11.

Under Palestinian law, collaboration with Israel is punishable by death.

All execution orders must be approved by the Palestinian president before they can be carried out, but Hamas no longer recognises the legitimacy of incumbent Mahmud Abbas, whose four-year term ended in 2009.

Following a deadly eight-day confrontation with Israel in November, the Hamas government announced the creation of a committee to examine the "unlawful executions" of Palestinians accused of spying for Israel during the conflict.

In at least two incidents during Israel's bombardment of the territory, seven people were gunned down after being accused of being collaborators.

The killings were claimed by Hamas militants from the Ezzedine al-Qassam Brigades.

Shahwan did not elaborate on the punishment a repentant "collaborator" could expect, but said he expected the offer to evaporate Israel's pool of informants in the strip.

"This campaign is a message we send to the Zionist enemy to assert the failure of its security and intelligence programme," he said.

"Sources of information about our people and our resistance in this manner will soon dry up."

Mohammed Lafi, an official with Gaza's internal security services told reporters that one of Israel's recruitment methods was to "blackmail" Gazans crossing for hospital treatment in Israel or the occupied West Bank.