Liberia's main opposition say they are withdrawing from a "fraudulent" presidential election vote-count. The parties, which include candidates in second and third place so far, said the National Election Commission has manipulated vote-counting in favour of President Ellen Johnson Sirleaf. Partial results show Mrs Sirleaf leading, but short of the majority needed to avoid a run-off vote. And the election commission later rejected the opposition charges. It has until 26 October to announce the final results. Under the rules, if no candidate scores an overall majority, a run-off between the two front-runners will be held early next month. The opposition say they will not accept the result if counting goes on. An opposition statement said: "We wish to notify the Liberian people of the massive fraud being carried out by the National Elections Commission in the handling and reporting of the presidential election results in favour of President Ellen Johnson Sirleaf and the Unity Party." The parties said they could offer photographs and witnesses to back their claims. "We direct all our party agents assigned at (the electoral commission) in all capacities to withdraw effective immediately," the statement read. "If the process continues we will not accept the results." Hours later, the National Election Commission chairman James Fromayah said: "It doesn't pose any credibility problems. All the parties participated in the elections. The counting was done and both the local population and the international observers that came acclaimed the process to be free, fair and transparent." Mr Fromayan said that if any party or candidate had qualms or reservations about the polls, they should channel their grievances through the complaints process. He said investigations on 12 cases were being carried out and ballot boxes from four polling places had been quarantined. The latest results published by the elections commission, with 80% of the votes counted, put Mrs Sirleaf on 44.6% of the vote, while her nearest rival, Winston Tubman polled 31.4% and former warlord Prince Johnson has 11.2%. Mrs Sirleaf's Unity Party said it was not surprised by the allegations. "They are doing this thing because it is not going their way," said party secretary-general, Wilmot Paye. "That's why they want to create chaos." Nobel peace prize This is the first election organised by Liberia's National Elections Commission - the previous one was run by the UN. But 8,000 UN peacekeepers were deployed across Liberia, helping the election to unfold in a quiet atmosphere. President Sirleaf, who was first elected in 2005, was awarded the Nobel Peace Prize last week - a decision denounced by Mr Tubman and other candidates. Mr Tubman is running under the banner of the Congress for Democratic Change (CDC) party, with ex-football star George Weah as his running mate. Mr Weah was beaten by Mrs Sirleaf in the 2005 poll. Prince Johnson's forces infamously filmed the torture and murder of dictator Samuel Doe in 1990. After the war, he became a born-again Christian pastor and was elected to the senate in the 2005 poll. Mrs Sirleaf had said she would only seek a single term but explained her U-turn by saying she wanted to finish the work she had started. While Mrs Sirleaf is well regarded by the international community, some analysts say she is less popular at home. Her challengers accuse her of not doing enough to improve the lives of ordinary people, who remain among the poorest in the world. Mrs Sirleaf has also been criticised for backing former President Charles Taylor - currently on trial at The Hague for alleged war crimes - when he began his rebellion in 1989. The pair later fell out and she apologised for her role, but Liberia's Truth and Reconciliation Commission said she should be barred from holding public office. Liberia is Africa's oldest republic - it was founded in 1847 by freed US slaves, hence its name.