SANA'A – Twenty-three Yemeni government soldiers have reportedly been killed by Houthi fighters in two separate incidents in northern Yemen, rebels said on Saturday. Fifteen Yemeni government troopers lost their lives in an ambush on a military supply convoy in the Wadi al-Jabara district, while the other eight soldiers were killed in clashes in the city of Saada. The Yemeni offensive against Houthis, which was joined by Saudi Arabia in November, has so far claimed the lives of many civilians and displaced thousands of others from their homes in northern villages. The developments came as the Houthi fighters offered to accept the six conditions for a truce originally set by the government at the end of last month. Yemen has stepped up its military operation in the region despite the offer by the Houthi leader to end the six-month conflict. Meanwhile, Yemen has set a timetable for Houthis to implement the government's terms for a ceasefire in their six-year-old uprising in the northern mountains, a presidential adviser said on Saturday. The details have been transmitted to rebel leader Abdul Malak al-Houthi through a go-between, Abdul Karim al-Ariani told reporters. "After the agreement by the Houthis to the six conditions, the high security committee has drawn up an implementation timetable which will be overseen by five parliamentary committees," Ariani said. "If they agree to it and sign it, the war will end immediately," he said. At the end of last month, the rebels offered to accept the five conditions originally set by the government for a ceasefire. But the government rejected the offer, saying the rebels also needed to accept a sixth key condition – a promise to stop attacking Saudi territory. The rebels said they had withdrawn from all of the Saudi territory that they occupied after border clashes in December but are continuing to come under Saudi attack inside Yemen. A statement on the rebels' website on Thursday said that Saudi air raids had killed 14 people, including women and children. As the peace feelers have faltered over the past week, there has been renewed fighting between the rebels and the army. On the other side, UN aid agencies have warned that a lack of funding is hampering their efforts to assist the estimated 250,000 civilians displaced by the conflict in north Yemen. "Our two camps [in Yemen] are overpopulated and we don't know if we'll be able to build a third one as we wanted," Melissa Fleming, a Spokesperson for the UN High Commissioner for Refugees (UNHCR), said on Friday. She further added that there was a major lack of funding for Yemen where the UNHCR helps some 250,000 displaced people in the north of the country, and another 170,000 refugees. "There are concerns that all the efforts are going to Haiti," which is coping with the aftermath of a devastating 7.0-magnitude quake, she went on to say. According to the UN Office for the Coordination of Humanitarian Affairs (OCHA) Spokeswoman Emilia Casella, the OCHA in November appealed for 177 million dollars for aid to Yemen this year. Casella further pointed out that the Agency had been forced to reduce daily food rations in Yemen. "If donor funds are not found in the next few weeks, it's likely to lead to further ration reductions and possibly the suspension of a number of programmes in Yemen by the end of the first half of this year," the spokesperson said.