CAIRO - The armed wing of Hamas called on Palestinian negotiators in Cairo not to extend a 72-hour truce unless their demands, in particular for the opening of Gaza's port, were met and warned it was ready to engage in a long war."We urge the Palestinian delegation negotiating not to renew the truce except after the acceptance in principle, particularly to the port (opening), and if there is no acceptance then we ask the delegation to withdraw from talks," a fighter, his face hidden behind a Palestinian scarf, said in a televised statement from Izz a-Din al-Kassam Brigades. The statement was aired on the Qatari-owned Al Jazeera news network.Meanwhile, the Egyptians were exerting pressure on Hamas and Islamic Jihad on Thursday to agree to the extension of the 72-hour cease-fire with Israel, which expires Friday morning at 8 a.m. Palestinian sources said that the Egyptians are hoping to persuade the two groups to agree to another 72-hour cease-fire.According to the sources, the cease-fire discussions in Cairo have thus far failed to achieve real progress.The sources attributed the lack of progress to Israel’s refusal to comply with the demands of Hamas and Islamic Jihad, including the release of West Bank Palestinians who were rearrested over the past two months and the construction of a seaport in the Gaza Strip.The sources said that Hamas and Islamic Jihad have also rejected Israel’s demand that they be disarmed as part of a cease-fire agreement.Representatives of the two groups reiterated Thursday their strong opposition to surrendering their weapons and threatened to resume attacks on Israel when the current cease-fire expires at 8.00am Friday. Hamas and Islamic Jihad are part of a Palestinian delegation headed by Fatah’s Azzam al-Ahmed that arrived in Cairo earlier this week for talks aimed at ending the fighting in the Gaza Strip.Members of the delegation held a series of meeting with senior Egyptian officials and presented them with a list of demands for a long-term cease-fire with Israel.The demands include the lifting of the blockade on the Gaza Strip and allowing Palestinians there to have run their own airport and seaport.Hamas leader Musa Abu Marzouk dismissed the possibility that the US would provide assurances regarding any deal between Israel and the Palestinians. “The only guarantee is the weapons of the resistance,” he wrote in a posting on Facebook. “America can’t act as a guarantor since it decided on the blockade and its weapons were used for destruction.”Hamas also threatened to resume its attacks on Israel unless an agreement to lift the blockade is reached in Cairo.The Al-Jazeera TV network quoted a source in the group as saying there would be no extension of the cease-fire unless all Palestinian demands are met. In Israel, senior security sources warned on Thursday evening that the Jewish state will respond with force if Hamas renews attacks. The sources said Prime Minister Binyamin Netanyahu and Defense Minister Moshe Ya'alon have instructed the military to be prepared for all scenarios. An army source added that Hamas has many reasons to want to end the current conflict, but that the army was not dismissing Hamas's belligerent declarations. "We are preparing. As an army we must take into account the possibility that at 8 am they will begin firing. We are ready for this."Israeli officials have said that Israel would accept an extension of the 72-hour unconditional cease-fire that expires Friday morning as long as that extension is also “unconditional.”Members of a team of five Israeli negotiators are reportedly shuttling back and forth from Cairo to Jerusalem. Yaakov Lappin and Herb Keinon contributed to this report.