Two thirds of Somalia's cabinet ministers resigned on Saturday, officials said, widening a rift between the president and prime minister that threatens to wreck the country's interim government. The 10 ministers who quit were all allies of President Abdullahi Yusuf, who has appeared increasingly at odds with Prime Minister Nur Hassan Hussein. This week, Yusuf revoked an order by Hussein sacking Mogadishu's powerful mayor. “I have resigned because the government has failed to implement its programmes and has gone against the charter,” Khadija Mohammed Diriye, the former family affairs minister, told Reuters in Baidoa, where parliament sits. She said 10 of her colleagues tendered their resignations, four of them from overseas. Somalia had 15 ministers. It was not immediately clear what effect the move would have on the work of the interim government, which has struggled to impose its authority on the chaotic Horn of Africa nations since coming to power at the start of last year. One Somali member of parliament who asked not to be named said one group of lawmakers were calling on Hussein to resign over alleged financial irregularities in his administration. At the centre of growing tensions between Yusuf and Hussein is a former warlord and close Yusuf ally, Mohamed Dheere. This week the prime minister sacked Dheere as mayor and governor of the capital, accusing him of allegedly mis-using public funds and blaming him for mounting insecurity. On Thursday, Yusuf revoked the order, officials said. Dheere's fighters have been battling Islamist rebels waging an Iraq-style insurgency of roadside bombs, mortar blasts and assassinations against the government and its Ethiopian allies. On Friday, a roadside bomb killed a Ugandan soldier serving with a small African Union peacekeeping force. The political rift came as mediators tried to capitalise on a truce signed at UN-hosted peace talks in Djibouti in June between the government and some of the opposition. Ahmedou Ould-Abdallah, the UN special envoy for Somalia, expressed concern and urged all parties to work together. “The Somali people knew there would be challenges on the path to peace and they should not be discouraged,” he said in a statement on Saturday. “The authorities should remain focused on peace and I hope to see them shortly ... We must keep moving forward to ensure the agreement is fully implemented as soon as possible.” The country's interim administration is the 14th attempt at forming a functioning central government since warlords toppled a military dictator in 1991, plunging the nation into crisis. The latest violence has killed more than 8,000 civilians since early last year and driven 1 million from their homes.