DR Congo\'s M23 rebels who have closed in on the main eastern city of Goma warned on Monday that they will continue their fight against the government unless it opens direct talks with them within 24 hours. The rebels said in a statement they will \"pursue the resistance against the government of Kinshasa until it falls\" unless it starts \"direct political negotiations\" with the insurgents within the next 24 hours and demilitarises Goma and the city\'s airport. The rebels, army mutineers whose uprising in April has unleashed fresh unrest in the country\'s mineral-rich but chronically restive east, were massed at the gates of Goma on Sunday despite efforts by government troops and UN helicopters to stop them. The United Nations has warned there was a real threat that Goma could fall to the rebels, who it says are being supported by neighbouring Rwanda and Uganda, charges both countries deny. The EU, Britain and France have also expressed alarm at the violence, which has displaced thousands of civilians and flared up again after a three-month truce on Thursday, just two days after the UN and the United States imposed sanctions on the M23 leader. In Goma on Monday, schools were shut and streets were deserted save for rare army or UN vehicles a day after the rebels advanced to near the airport, just a few kilometres outside the city itself.As government troops and local officials fled the city, according to several sources, the regional governor Julien Paluku said he was staying and appealed for residents to do the same. \"There is nothing to fear, the city is protected by the international community,\" he said according to his spokesman. UN chief Ban Ki-moon vowed on Sunday that peacekeepers would stay in Goma. The UN troops \"will remain present in Goma and will continue all efforts to robustly implement its mandate to the fullest of its capabilities with regard to the protection of civilians\", he said. The United Nations has about 6,700 troops in Nord Kivu province, backing government forces against the rebels. About 1,500 of them are in Goma, deployed in \"quick reaction units\". UN attack helicopters have staged cannon and rocket strikes against the rebels but have not been able to stop the steady advance towards the capital of Nord Kivu, a key mineral producing region in the vast central African nation. In New York, UN peacekeeping spokesman Kieran Dwyer told AFP that UN forces were supporting government troops in the region by firing cannon and rockets at the rebels, after similar action on Saturday. \"The situation in Goma is extremely tense. There is a real threat that the city could fall into the M23\'s hands,\" said Dwyer. The M23 rebels are ethnic Tutsi former soldiers who mutinied in April after the failure of a 2009 peace deal that integrated them into the regular army. UN experts have said Rwanda and Uganda back the rebels, a charge fiercely denied by both countries. The EU on Sunday joined the UN in calling on the rebels to halt their advance. The UN Security Council held an emergency session on the crisis on Saturday, demanding an end to the M23 advance and \"that any and all outside support and supply of equipment to the M23 cease immediately\". It also vowed fresh sanctions against M23 leaders and those who help it breach UN sanctions and an arms embargo. The fighting is the most serious since July, when UN helicopters last went into action against the M23.