Street protests shook Georgia\'s rebel region of South Ossetia for the second day Thursday as Russia tried to defuse a political crisis sparked by the invalidation of leadership polls. Opposition leader Alla Dzhioyeva, who proclaimed herself president despite a supreme court decision to cancel poll results, said she sent a written ultimatum to the outgoing leader of the Moscow-backed province, and hundreds of her supporters protested for a second day. Dzhioyeva called on outgoing president Eduard Kokoity to reverse the annulment of results by 1800 local time (1400 GMT) and recognise her unexpected weekend victory over a candidate backed by South Ossetia\'s patron Moscow. \"In the event that these demands are not fulfilled, all responsibility for further developments in the situation will lie wholly with the leadership of the republic,\" she said in the letter, Interfax news agency reported. Hundreds of Dzhioyeva\'s supporters stood in protest outside the government building in the capital of the impoverished province until the early hours on Thursday despite heavy snowfall, with some burning fires to keep warm. Russian presidential administration official Sergei Vinokurov flew in from Moscow to discuss the situation with Dzhioyeva in the early hours of Thursday, in what she called \"constructive dialogue\", without giving further details. Security forces fired warning shots on Wednesday to prevent her supporters from breaking into a government building, but the local security service, which still goes by its Soviet-era name KGB, has said it will not suppress peaceful protests. Dzhioyeva however expressed fears of a possible crackdown by the authorities. \"Nothing can be ruled out. These people are capable of anything,\" she said, according to Interfax. She also appealed to Russian President Dmitry Medvedev for support, warning that the region was on the brink of \"civil war\". Moscow recognised the independence of South Ossetia and another breakaway Georgian region, Abkhazia, shortly after the 2008 conflict with Tbilisi despite other world powers insisting both territories remain an integral part of Georgia. The supreme court of South Ossetia has scheduled a new election for March 25. The election commission had Dzhioyeva leading Sunday\'s second round runoff ballot with 56.7 percent when the vote was annulled because of alleged violations by her supporters. Georgia said fair elections were impossible because the territory is \"occupied\" by thousands of Russian troops stationed there since the 2008 war, when most ethnic Georgian inhabitants were expelled. The population of the tiny region is also a subject of dispute, with the rebel authorities claiming 70,000 while Georgia says the figure is no more than 15,000.