GAZA CITY (AFP) - Hamas agreed on Monday to hold fire against Israel for 24 hours, but warned it would resume suicide attacks if the Jewish state launched an offensive against its Gaza stronghold. The Hamas and other armed factions in Gaza have accepted "a calm for a 24-hour period following Egyptian mediation in exchange for the delivery of aid from Egypt," senior Hamas official Ayman Taha told AFP. Despite the brief ceasefire, Taha warned that Hamas would resume suicide attacks if Israel made good on its threats to unleash a major assault against the Gaza Strip. "It is our right as an occupied people to defend ourselves from the occupation by all means possible including suicide attacks," he said. Israel on Monday began a campaign to muster international support for any major offensive to try to halt rocket fire from the impoverished Palestinian territory. Tensions have mounted since the expiry on Friday of a six-month truce between Israel and Hamas in and around Gaza. In a letter to UN chief Ban Ki-moon, Israel's envoy to the United Nations, Gabriela Shalev, said the government would respond to continuing rocket fire, foreign ministry spokesman Yigal Palmor said. Foreign Minister Tzipi Livni, leader of the main governing Kadima party, has ordered Israeli ambassadors around the world to emphasise that Israel "will not hesitate to react militarily if necessary" to protect its citizens. She is also due to meet foreign envoys to Israel and speak with her counterparts abroad. "We cannot accept a situation where Hamas continues its attacks on the citizens of Israel," she said in a telephone call with US Secretary of State Condoleezza Rice. Israel has threatened a major offensive against the impoverished territory that has been controlled by Hamas since June last year. The two frontrunners in the race to become prime minister after a snap election in February " Livni and Benjamin Netanyahu, who heads the opposition Likud party currently leading in opinion polls " both vowed to oust the movement, sworn to the Jewish state's destruction. A convoy carrying a million dollars of Egyptian food and medical aid is expected to enter Gaza after Hamas declared the 24-hour truce. An official in El-Arish, 30 miles from the Rafah border crossing between Egypt and the Gaza Strip, said the aid had been waiting there since Sunday but had not been allowed in because of Palestinian rocket fire. Meanwhile Turkish Prime Minister Recep Tayyip Erdogan told Ismail Haniya, head of the Hamas administration in Gaza, by telephone that he would urge his Israeli counterpart Ehud Olmert during talks in Ankara to lift the blockade, a spokesman for the movement said.