Israel condemned the idea, which would mark the first time armed groups have been part of a Palestinian cabinet.

Israel and the United States have demanded Abbas disarm and dismantle militant organisations, as dictated by a US-backed "road map" to peace.

Hamas spokesman Sami Abu Zuhri said his faction, which has spearheaded a suicide campaign against Israel and is sworn to its destruction, would discuss the offer and "announce its decision in suitable time."

However, Islamic Jihad leader Nafez Azzam said his group, which has also killed hundreds of Israelis in attacks, had rejected the invitation, saying it "would not take part in a Palestinian government as long as (Israeli) occupation exists."

Samir al-Mashrawi, a Palestinian Authority negotiator and top leader in Abbas's Fatah faction, said he had invited the militant groups to discuss the formation of a unity government whose prime agenda topic would be Israel's pullout plan.

"The offer was prompted by the need to have a national partnership to shoulder responsibility in this very delicate and sensitive situation," he said, adding that such a move would not affect an upcoming legislative election.

Hamas's popularity has grown during more than four years of violence, especially in Gaza, where it made a strong showing in municipal elections earlier this year. Hamas also plans to challenge Abbas's Fatah group in the coming election.

Israeli Foreign Ministry spokesman Mark Regev said Israel sees the group as "part of the problem and not as part of any sort of solution" and reiterated Israel's demand that Abbas dismantle it.

Meanwhile, dozens of militants linked to Palestinian President Mahmoud Abbas's Fatah group raided a government building in Gaza on Saturday, demanding he make good on a deal to recruit them into his security forces.

About 40 armed men from the Al-Aqsa Martyrs Brigades, some masked, stormed the Legislative Council building in the town of Rafah and occupied it for four hours. They said they had not used violence or held anyone hostage.

The Palestinian Interior Ministry called the protest "useless" and said committees were still discussing the issue of hiring the men. Al-Aqsa is linked to Fatah, the main Palestinian faction.

"The ministry ... will not succumb to any blackmail attempt made by any of the armed groups," the ministry said in a statement. "The ministry and its agencies will not hesitate to impose the law and protect private and public properties."