DOHA - Chad’s military government and more than 40 opposition groups signed a deal Monday to launch national peace talks this month, but the main rebel outfit refused to take part. United Nations and African Union leaders urged the junta and opposition to seize the latest opportunity to stabilise a country considered key to international efforts to stamp out Islamic extremists in the Sahel region. But after five months of mediation efforts by Qatar, the main rebel Front for Change and Concord in Chad (FACT) announced hours before the ceremony in Doha that it would not join. And several other armed groups, including the Military Command Council for the Salvation of the Republic, also refused to sign the agreement. Under the deal, Mahamat Idriss Deby’s Transitional Military Council and hundreds of opposition representatives will launch a national peace dialogue in the capital, N’Djamena, on August 20. Deby, who was in Doha for the signing, took power after his father, long-time president Idriss Deby Itno, was killed in April last year shortly after taking personal charge of a counter-offensive against the rebels. The dialogue aims to agree the rules for a presidential election that Deby has promised by October.  Chad, one of the world’s poorest countries, has endured repeated uprisings and unrest since independence in 1960. Deby promised a national dialogue and elections within 18 months after seizing power, but the mediation has been fraught since the first day when FACT and other groups walked out of the launch ceremony.