The fragile Gaza ceasefire and the prisoner deal with Hizbollah have emboldened Hamas to demand a larger number of Palestinian prisoners in return for the captured Israeli soldier Sergeant Gilad Shalit.

Sporadic firings on Israel from the Gaza Strip have not caused the ceasefire to break down, despite at least four occasions on which Palestinians have fired mortars and Kassam missiles since the ceasefire began two weeks ago.

Israel’s response has been to close the crossings into the Gaza Strip for a day at a time, but the IDF has not attacked in the Strip so far. Hamas has also begun to act against rival organisations, warning them not to break the ceasefire and even arresting a number of Fatah members involved in the firings.

Hamas leaders stressed that the arrests were carried out because they had “harmed Palestinian interests”.

Prime Minister Ehud Olmert said:  “You can’t impose total calm in a short time, so we have shown patience, but no one should interpret it as weakness. If the calm doesn’t prevail, we will retaliate with full force.”

The next stages of the ceasefire were supposed to be stepped-up negotiations over the release of Sergeant Shalit and the opening of the Rafah crossing into Egypt. But the talks have stalled due to Hamas delays. “They feel confident now there is a ceasefire and the supplies are coming through the crossings again,” a source close to the negotiations told the JC, “so they are not in any hurry. In addition, the deal that Israel signed with Hizbollah this week creates competition. Hamas wants to show they can get a much better deal.”

Israel is prepared to release about 450 prisoners in exchange for Corporal Shalit’s release, but Hamas is demanding a much higher number, including senior leaders and those convicted of murder, including Fatah leader Marwan Barghouti.

Khaled Mashal, head of Hamas’ political bureau, said in an interview this week with Italian newspaper La Stampa that the Israelis “are concerned only with releasing the prisoner Hamas captured, we have 11,600 Palestinians in the Israeli prison, many of them civilians. The negotiations are for the exchange of these prisoners, not just Shalit.”