KHARTOUM, Jan 8 (Reuters) - The United Nations said on Saturday it would invite Sudanese military leaders, political parties and other groups to take part in discussions aimed at ending a crisis unleashed by a coup in October. U.N. mediation in the weeks after the coup succeeded in reinstating Prime Minister Abdalla Hamdok, but his resignation last week deepened uncertainty around Sudan"s political future and a transition towards elections scheduled for 2023. read more Neighbourhood-based resistance committees, political parties and other pro-democracy groups have carried out an ongoing campaign of protests under a "no negotiation" slogan, and crackdowns by security forces have left at least 60 dead. "All measures taken to date have not succeeded in restoring the course of this transformation," U.N. Special Representative Volker Perthes said in a statement announcing the launch of the U.N.-facilitated dialogue initiative. "The ... repeated violence against largely peaceful protesters has only served to deepen the mistrust among all political parties in Sudan," he added. Sudan"s military, armed movements, political parties, civil society and resistance committees will be invited to participate, the U.N. statement said. Unless a new course towards a transition and credible elections can be charted, more instability within and beyond Sudanese borders is likely, analysts and diplomats have said. The Quad group, comprising Saudi Arabia, the United Arab Emirates, Britain and the United States, voiced backing for the U.N. effort. "We strongly support this UN-facilitated, Sudanese-led dialogue initiative," a group statement said. "We urge all Sudanese political actors to seize this opportunity to restore the country"s transition to civilian democracy." Sudan"s main civilian opposition coalition, the Forces of Freedom and Change (FFC), said in a statement it welcomed "any international effort that contributes to achieving the goals of the Sudanese people in combating the coup and establishing a civil and democratic state".