Hamas today lashed out at militants from rival Palestinian groups, claiming that they were deliberately trying to wreck the fragile Gaza truce with Israel to "settle internal scores".

As more rockets were fired from Gaza into the Jewish state, both Israeli and Palestinian officials expressed doubt over the likelihood of the truce surviving its intended six-month span. The total number of mortars launched at Israel now numbers seven since the week-long Egyptian accord began.

The truce had seen Hamas pledge to stop cross-border rocket fire and for Israel gradually to ease its embargo on the Gaza Strip, imposed after Hamas militants drove out President Mahmoud Abbas's Fatah in a military coup last summer.

After increasing the amount of humanitarian aide into Gaza by 30 per cent this week, Israel resealed the border crossings when the first mortars violated the truce on Tuesday, causing infrastructure damage and slightly injuring two Israelis.

Hamas today lashed out for the first time at militants who it claims were trying deliberately to breach the ceasefire to destroy the Islamists' grip on the territory. Today's rocket-attacks have been claimed by the al-Asqa Martyrs Brigades, a military splinter group of Fatah.

"It has become clear that some Palestinian parties do not want this calm deal to succeed and they do not want the siege to be lifted," Mushir al-Masri, a Hamas spokesman, said. "Those who fired the rockets did not aim them at the Zionist enemy but fired them to settle internal scores."

Islamic Jihad said that last Tuesday's rocket attack was in retaliation for the Israeli Army's killing of one of its commanders in the occupied West Bank, where the ceasefire does not apply. However, the al-Aqsa Martyrs Brigades used the same reasoning for today's attack, a move which Hamas said showed its ulterior motive.

Questions today remained as to if — or when — Israel would respond formally to the rocket fire. Key members of Ehud Olmert's Government including, Ehud Barak, the Israeli Defence Minister, and Tzipi Livni, the Foreign Minister, are thought to have argued for military action in Gaza. Ms Livni today said: "I don't care who fired. There must be an immediate military response to every violation."

Meanwhile, Israel appeared closer to negotiating a deal for the release of the kidnapped Israeli soldier Gilad Shalit today.

Yuval Diskin, the Shin Bet security service chief, has agreed to release some Palestinian prisoners "with blood on their hands" — a phrase used by Israel to describe those directly involved in terrorist attacks — in exchange for Corporal Shalit, who was captured two years ago today, and is presumed to be alive.

Israeli political insiders believe that the Israel Defence Force’s hesitation in entering Gaza in a large-scale military operation stems largely from fears that he could be killed by his captors in a revenge attack.

The Arabic-language newspaper Al Hayat reported yesterday that the terms of the deal would see 150 Palestinian inmates released in the first stage, in return for Corporal Shalit being transferred to Egypt, where his family would be able to visit him. On the soldier's return to Israel, 800 additional prisoners would be released in two stages.

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