JERUSALEM (AFP) - Israeli caretaker Prime Minister Ehud Olmert said on Monday 250 Palestinian prisoners would be freed in a goodwill gesture towards Palestinian President Mahmud Abbas, who in turn urged Israel to maintain the Gaza truce. The pair met in Jerusalem for the first time in two months, amid rising tension in and around the besieged Gaza Strip where Israeli forces and Palestinian fighters have engaged in almost daily tit-for-tat attacks since November 4. "Abbas had asked him to free Palestinian prisoners and Olmert told him of the decision to release 250 at the beginning of December," Palestinian negotiator Saeb Erakat said. In a similar move in August, Israel freed 198 Palestinian prisoners. More than 11,000 Palestinians are still held in Israeli prisons. A senior Israeli official said that none of the prisoners to be freed belongs to Palestinian movements such as Hamas, the movement that seized power in the Gaza Strip in June 2007. Since the Hamas takeover, the secular Abbas has held sway only in the West Bank. But during Monday's talks at Olmert's official residence, Abbas "stressed the need to maintain the truce and to meet humanitarian and food needs in the Gaza Strip," Erakat said. A convoy of humanitarian aid was allowed into the Gaza Strip on Monday for the first time since Israel responded to a flare-up of violence by completely sealing off the territory on November 5. "The transfer of 33 aid trucks carrying food, medicine and medical equipment have been completed at the Kerem Shalom crossing," the Israeli army said in a statement. Olmert told Abbas that Hamas is to blame for violations of the truce in and around the Gaza Strip, and warned that if violence escalates, "Israel will have to respond," a senior Israeli official said. On Monday at least half a dozen rockets fired from Gaza hit southern Israel without causing any casualties. Each side has accused the other of violating the ceasefire in the latest flare-up of violence in which volleys of rockets and mortar rounds have been launched at Israel and 15 Gaza fighters killed since Nov 4. Israel generally responds to the Gaza attacks by tightening the blockade it imposed after the 2007 Hamas takeover, but said it allowed 33 truckloads of humanitarian supplies into the coastal strip on Monday. A UN spokesman said that many more deliveries would be needed in the impoverished and overcrowded territory where it distributes food to 750,000 people " half the population. "We cannot have another period when people are not getting their food assistance. We cannot allow people to get punished in that way," said Chris Gunness of the UN Works and Relief Agency. Israel had been expected to ease its embargo after the truce, intended to last six months, went into effect in June 19, but it argues that attacks by the fighters have made this impossible.