Two opposition frontrunners in Democratic Republic of Congo's long-awaited presidential election refused on Saturday to sign a peace pact on the eve of a poll that has stirred fears of violence in the volatile nation.With tensions rising before the vote, Martin Fayulu and Felix Tshisekedi rejected a proposed pledge aimed at averting post-election violence, saying election officials had failed to make suggested changes to the text.They announced their decision after a brief meeting with African election observers.Voters are to cast ballots on Sunday to decide who will replace President Joseph Kabila, stepping aside after nearly 18 years at the helm of the vast, resource rich nation that has not known a peaceful transfer of power since independence in 1960.The country's Independent National Election Commission (CENI) had sought to persuade the two opposition heavyweights, and Kabila's preferred successor Emmanuel Ramazani Shadary, to sign a pact aimed at preventing violence after the result was announced.The text, which had not been seen by AFP, was a "commitment to peace, for transparent, calm and non-violent elections", according to the head of the commission, Corneille Nangaa. Fayulu, until recently a little-known legislator and former oil executive, said earlier that both he and Tshisekedi declined to sign an initial draft but had promised "to sign the agreement incorporating the amendments."Fears of unrest have soared after a warehouse fire destroyed thousands of voting machines earmarked for the capital Kinshasa, prompting the election commission to order a last-minute postponement of the vote from December 23 to 30.They had already been delayed by two years.On Wednesday, CENI declared the vote would be postponed again in violence-hit parts of the country, while insisting the rest of the national vote would go ahead.The announcement prompted Lamuka, a coalition of parties supporting Fayulu, to call for cities to be brought to a standstill on Friday. Those protest calls did not gain much traction, but there was violence in the eastern province of North Kivu, one of the regions where voting has been postponed.Around 1.25 million people in North Kivu and the southwestern territory of Yumbi are affected by the postponement, out of a national electoral roll of 40 million.One demonstrator was shot dead in the city of Beni and four were wounded, local sources said.However, Kabila said he was confident "everything will go well on Sunday"."I want to reassure our people that measures have been taken with the government to guarantee the safety of all sides, candidates, voters and observers alike," he said in his end-of-year address broadcast on Saturday evening on the RTNC state television.Polling stations are to open at 0400 GMT and close at 1600 GMT. 'Fear covers our hearts' DRC is mired in poverty, despite mineral riches ranging from gold and uranium to copper and cobalt. The nation has been a battleground for regional wars twice in the past 22 years.Kabila took office in 2001 at the age of just 29, succeeding his president father, Laurent-Desire, who was assassinated by a bodyguard.The presidential election - its first in seven years - coincides with voting for municipal and legislative bodies.A question mark now hangs over whether the vote will be credible. The authorities have permitted some election monitors from fellow African countries but refused any financial or logistical help from the UN or western countries.Tshisekedi, head of a veteran UDPS opposition party, has encouraged voters to remain near polling stations after voting ends. But Congolese police on Saturday warned they would arrest anyone loitering near polling stations after they close."We appeal to the understanding of our fellow citizens to trust the various witnesses of the candidates, who have received accreditation for the vote and counting operations," colonel Pierrot Mwana Mputu said in comments broadcast by state television. Earlier on Saturday, church leaders from the country's powerful Christian denominations held a service calling for peace."Worries still loom over our heads and fear covers our hearts," said archbishop of Kinshasa, Fridolin Ambongo. "The divergence of ideas is no reason to set fire to the country."* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.