The majority of the faction's most senior political figures outside Gaza were detained in an unexpected nocturnal sweep early yesterday, which Palestinians swiftly interpreted as a move to dislodge the Hamas government and which the Group of Eight industrialised countries said raised " particular concerns".
The Israel Defence Forces said last night that those arrested, who include Omar Abdel Razeq, the Finance Minister, Nasser Shaer, the Deputy Prime Minister, and six of their cabinet colleagues, would be brought before a judge to extend their detention and that indictments would be filed against "those who are deemed sufficiently suspect of criminal activity".
Israeli air strikes in Gaza City also destroyed the Interior Ministry and an office belonging to President Mahmoud Abbas's Fatah group.
As the military pressure continued with artillery barrages directed at open ground in the northern Gaza towns of Beit Hanoun and Beit Lahiya, reports in Israel said Ehud Olmert, the Israeli Prime Minister, had ordered the incursion into Beit Hanoun planned for last night to be delayed.
The reports came as Hosni Mubarak, the Egyptian President, told the daily Al Ahram newspaper that he had asked for the delay after Hamas had made a " conditional agreement" to hand over Gilad Shalit, the 19-year-old army corporal who was abducted by Palestinian militants including members of Hamas's armed wing on Sunday. But he added that Israel had not yet accepted.
A leaflet dropped on Beit Hanoun earlier by Israeli forces warned residents to keep off the streets during the operation the first since Israel's withdrawal from Gaza last August and that anyone who sought to disrupt the IDF mission would be "in danger".
The body of a Jewish settler from the West Bank settlement of Itamar, Eliyahu Asheri, 18, whom the Palestinian Resistance Committees (PRC), another of the groups responsible for Cpl Shalit's abduction, had claimed to have kidnapped, was found in a field in Ramallah early yesterday, and buried at the Mount of Olives cemetery in Jerusalem.
In a separate development in southern Gaza, where Israeli troops have taken control of the disused Gaza international airport, hundreds of Palestinian and Egyptian police on both sides of the Gaza-Egypt border at Rafah formed a human cordon to try to prevent Palestinians rushing to get through a hole blasted in the concrete border wall by militants saying were members of Hamas's military wing.
The West Bank arrests of the Hamas political figures, along with another 23 identified as militants by Israel, provoked a furious reaction even from its Fatah rivals. Five of the ministers were arrested in the same Ramallah hotel while a fifth, Mohammed Barghouti, was stopped by a military jeep as he drove to his home just north of the city.
As President Abbas called on the UN to intervene, one of his allies, Saeb Erekat, the chief Palestinian Liberation Organisation negotiator, said: "We have no government, we have nothing. They have all been taken. This is absolutely unacceptable and we demand their release immediately."
Israel's Foreign Ministry said the arrests had been justified by Hamas's willingness to claim responsibility for Qassam rocket attacks on Israel over the past two and a half weeks, an open resort to militancy, which had reached a "crescendo" with its military wing's involvement in the raid on an Israeli border post on Sunday in which two Israeli soldiers were killed and Cpl Shalit abducted. "Hamas can't get back into the terrorism business and not expect us to respond," said Mark Regev, the ministry spokesman.
Palestinian engineers managed to redistribute six hours of electricity to people cut off on Wednesday but there were further attacks on the power plant.
At the Beit Hanoun Palestinian National Security depot, half a mile, from the Israeli border at Erez, on the other side of which tanks and troops have been massing, Sergeant Nasser Tibi said that as soon as they saw Israeli forces advancing they would inform their superiors and then withdraw. " The resistance may act but not here in open land."
Inside the town, Basil Hamad, 42, a teacher at the Islamic University, said amid the repeated sounds of artillery shelling: "There may be resistance but ... there is no comparison between the strength of Israeli forces and the weakness of the Palestinians." Mr Hamad said he believed Cpl Shalit was still alive and was shocked to hear of the death of the settler. "It is not our way," he said. "There should be an exchange of prisoners and the whole world should back it."
In contrast to Rafah, there was little sign of panic buying in Beit Hanoun. But the IDF leaflet makes it clear that the army will continue its operations until Cpl Shalit is rescued and it can "protect the security of Israeli citizens" a reference to the Qassam rockets frequently fired from the town.