Beirut - The United Nations has announced that UN-sponsored political talks between the Syrian government and opposition groups have been postponed from February 8 until February 20, partly to try to solidify the cease-fire.UN special envoy Staffan de Mistura, who will oversee the talks, said that "if the cease-fire becomes as solid as we hope that will only help the serious talks to actually be concrete."He said the UN also wants to give Syria's government a chance "to become seriously engaged in concessions" and to give the opposition time to unify its delegation.De Mistura said invitations will be issued around February 8. He said that if the opposition isn't united by that date, he will select the delegation himself and ensure it is as inclusive as possible, including adding women, which has not previously been the case.The cease-fire, which took effect December 30, is broadly working "quite effectively," he said."The sooner we have a stable cease-fire and a political process, there will be a much easier possibility for everyone to focus on priority one, which is fighting the terrorist organisations identified by the Security Council," the Islamic State and the al-Qaeda affiliated Fatah al-Sham Front, previously known as the Nusra Front, de Mistura said.Thousands trappedOn the ground in Syria, the UN World Food Program said it resumed food airdrops to besieged Deir al-Zour in eastern Syria after the Islamic State group renewed its assault on the city two weeks ago.Militants cut off the remote city from its airport in a major offensive January 15, a UN humanitarian adviser said at the time, and the airport is the only link to the outside world.Islamic State extremists, who laid siege to Deir al-Zour in 2015, also captured the UN's primary drop zone, forcing the WFP to suspend relief deliveries for two weeks. The agency located a new drop zone and began delivering aid again Sunday.The UN's Jan Egeland estimated 93 000 civilians were trapped inside Deir al-Zour. Thousands of soldiers and loyal militiamen are also caught up in the siege.The activist group Justice for Life Deir el-Zour, which maintains a network of contacts in the city, has accused the government and loyal militias of hoarding supplies as they are flown in.Deir al-Zour natives told the AP last year they had to bribe government officials to escape via the airport. They said commanders were gouging food prices and profiting off the war economy.De Mistura said that solidifying the cease-fire should allow greater humanitarian access to besieged and hard to reach areas of Syria.He said several elements that give the current cease-fire a greater chance of holding, but they need work.New monitoring mechanismThe UN envoy cited last week's meeting in Kazakhstan's capital of Astana, where organisers Russia and Iran, both allies of the Syrian government, and Turkey, which backs the opposition, all pledged support for the cease-fire and agreed to act as guarantors.De Mistura noted that 13 armed groups attended the two-day meeting and there is a "serious intention" to establish a mechanism to monitor the cease-fire, which was missing in previous Syrian cease-fires.He said Security Council members welcomed a follow-up technical meeting in Astana on February 6 on the establishment of this mechanism, and the UN will be there to offer its expertise on implementing cease-fires and truces.In the campaign against the extremists, fighting continued for the second day in the southern Daraa province between the rebels and an Islamic State-affiliated group, the Khalid bin Walid Army, according to the Britain-based Syrian Observatory for Human Rights monitoring group.The Observatory said at least 20 fighters from either side have been killed.Rebels, al-Qaeda linked insurgents, IS militants, and government forces and loyal militias are all skirmishing for control of Syria's southern provinces.