Egyptian efforts to broker a truce with Israel have been held up since Tuesday, the day on which President Mohamed Morsi vowed the “farce of the Israeli aggression will end”. Some observers predict the truce will begin once US Secretary of State Hillary Clinton arrives in Cairo but the situation remains too close to call after Clinton met with Palestinian President Mahmoud Abbas in Ramallah and with Israeli Prime Minister Binyamin Netanyahu. An explosion hit a bus in Tel Aviv on Wednesday wounding at least 10 people. In a message on twitter a spokesman for Netanyahu said police were combing the area for the person who planted the device, implying that it was not a suicide attack. Israeli media said a man had been arrested. Hamas spokesman Sami Abu Zuhri praised the bombing. “Hamas blesses the attack in Tel Aviv and sees it as a natural response to the Israeli massacres... in Gaza,” he told Reuters. “Palestinian factions will use all means to protect Palestinian civilians in the absence of international efforts to halt the Israeli aggression.” Dozens have been killed as Gaza continues to be bombarded from sea and air. Meanwhile, Hamas officials have been waiting as Egyptian mediators communicate with Israel in order to finalise conditions for a truce. The two sides had already worked out a general framework for a truce but after five hours of negotiating agreement over the details remained as elusive as ever and both sides escalated their assaults. Some Israeli cabinet members insisted Hamas would emerge the victor if a truce agreement is concluded now. Defence Minister Ehud Barak was the only one of the eight ministers present to approve of the formula for a truce. Other obstacles to a cabinet agreement were objections voiced against the statement issued by President Morsi while attending his sister's funeral. Morsi's statement that the “farce of the Israeli aggression will end” led Israeli officials to complain that it signalled a lack of neutrality on the part of the Egyptian mediator. Other parties in Israel focussed on the rest of the Egyptian president's statement in which he said, “We want a genuine peace”. Some sources maintain that Hamas leader Khaled Meshaal was responsible for delaying a halt in hostilities, arguing that in telling the media “Netanyahu is the one who asked for a ceasefire” Meshaal made it clear Hamas was determined to portray any ceasefire as a victory, something Israel would not accept. A Hamas official participating in the negotiations in Cairo told Al-Ahram Weekly: “The negotiations are proceeding in one direction from our side. There has to be a return to the situation as it stood before last week. In addition, there have to be guarantees of a halt to all operations targeting the political and security leaders of Palestinian factions, and the blockade must be lifted at all crossings, by which we mean not just the Rafah crossing but crossings on the Israeli side as well. This must go into effect simultaneously with the ceasefire.” An Egyptian source said that “Israel wants guarantees from Cairo that Hamas will not try to rearm itself while Hamas wants the Egyptian president's office and not security agencies to be the official guarantor of the truce.” Some Palestinian sources say there have been Israeli proposals for an “armistice” rather than a “truce”. They explain that a truce is a provisional ceasefire agreement between two parties for a specified period. In this case Israel has asked for 90 days as a preliminary period so as not to saddle any new government in Tel Aviv with responsibility for the agreement. An armistice is of longer duration during which the sides test the genuineness of each other's intentions with respect to an enduring peace. Egyptian sources say Israeli conditions for a 15 to 20 year armistice are unworkable. Hamas knows that Israel will make few concessions and the Palestinian factions will not accept to hand in their weapons. Nor will Israel agree to Hamas's conditions for an armistice, which would include the dismantling of Israeli settlements, withdrawal from Jerusalem and the right of return for Palestinian refugees.