Yemeni forces killed 20 Houthi rebels on Sunday, effectively rejecting a ceasefire offer two days after it was revealed that over a quarter million Yemeni civilians have been displaced by the conflict. Abdel Malik Al-Houthi, the leader of the Shia rebellion in Yemen's northern provinces, announced Saturday that his forces would accept five conditions set by the Yemeni government for a ceasefire after Yemeni national forces stopped "aggression" in the area. The leader seemed to frame his acceptance of the ceasefire as a response to the growing humanitarian crises the conflict has created. "In order to avoid the catastrophic situation in the country and to stop the genocide which civilians are exposed to, we reiterate our acceptance of the five conditions," Al-Houthi said in an online audio recording. But without responding to Al-Houthi's statement, Yemen's Ministry of Defense announced Sunday that its soldiers had killed 24 Houthi rebels in air raids throughout the northern provinces of Malahidh and Saada. The news came just two days after the United Nations High Commissioner for Refugees (UNHCR) announced that the number of Yemeni civilians displaced since the fighting in the north broke out in 2004 has passed the 250,000 mark. The UN Refugee Agency estimates that the number of internal refugees has more than doubled since the latest round of fighting broke out in August 2009. "These are all people displaced by the fighting in the North," Andrej Mahecic, a spokesperson with UNHCR told The Media Line. "Those who fled left almost everything they had so they are facing incredible difficulties." "What we've noticed over the past two months is that those who tried to stay cannot sustain themselves any longer so they are now heading south," he said. "The livelihood that these people had has been destroyed. There are problems with the water supply and people simply cannot sustain themselves any longer where they live." "Making ends meet is getting increasingly difficult for the displaced population as well as access to basic services such as health and education," UNHCR said in a statement. "Most of them fled leaving behind almost all of their belongings and cattle which was the pillar of their livelihoods and primary source of income." "The need for humanitarian aid has been increasing dramatically so we are appealing for funds," said Mahecic.UNHCR said the lack of shelter for the 250,000 internal refugees was a major concern and is appealing for $16 million to serve those internally displaced in the north. The UN Refugee Agency welcomed the potential ceasefire. "Our biggest difficulty is access as it's very unsafe to move," Mahecic said. “From the start of the conflict secure access to the region has been a top issue for us. A minimum security environment is required to allow people to leave and to allow for the delivery of aid." Dr Ahmed Saif, a political scientist at the Yemen College of Middle Eastern Studies, argued that the ceasefire was born of international pressure and as such was likely to hold. "This is clearly an outcome of the London conference," he told The Media Line, referring to a gathering of major world powers in London last week to discuss developments in Yemen and Afghanistan. "The international community has put a great deal of pressure on all sides to reconcile so as to stabilize the country, build up security and fight Al-Qaeda." "I'm optimistic," Saif said. "The government set five conditions and the rebels accepted them. This cease-fire will be coordinated worldwide on many levels and hopefully set the stage for genuine reform in the country." The government conditions included the full withdrawal of Houthi rebels from all areas they have occupied in the course of the fighting, the return of all government and military equipment the rebels seized in the course of the fighting, the release of all detained soldiers and civilians and a commitment to abide by Yemeni national law. Dr Stephen Steinbeiser, Resident Director of the American Institute for Yemeni Studies in the Yemeni capital Sanaa, said that while it was too early to tell, the ceasefire held promise.”Most people are skeptical when they hear of a ceasefire in the north and I heard from the Red Crescent there was still fighting through the end of last week so it's difficult to know exactly what's going on," he told The Media Line. "But it sounds like there is a ceasefire and this is definitely a new development." "It could just be a short term stop in the fighting, but the Houthis seem to be serious about it," Dr Steinbeiser said. "The government forces have been effective in preventing the rebels from regrouping and bringing in arms and seem to have won, at least temporarily, in that area of the country, so in a way I don't know what choice the rebels have at this point."