Afghan presidential candidate Abdullah Abdullah has told thousands of supporters he plans to declare victory as he claimed massive fraud was responsible for preliminary results putting his rival ahead.
The United States has warned both camps against trying to seize power, saying international financial and security support is at stake.
The turmoil came as violence escalated around the country. A suicide bomber struck Afghan and foreign forces near a clinic in the eastern province of Parwan, killing at least 16 people, including four Czech soldiers. The Taliban claimed responsibility.
Mr Abdullah said he received calls from US president Barack Obama and secretary of state John Kerry, and he was told Mr Kerry would fly to the Afghan capital Kabul on Friday to help defuse the crisis.
State department officials with Mr Kerry in Beijing declined to comment on his travel plans.
Mr Abdullah told his supporters that the results of the election were fraudulent, but asked them to give him a few more days to negotiate.
He said: "We denounce and do not accept the results of the fraudulent vote. I assure you people of Afghanistan that I will sacrifice for you, but I will never accept a fraudulent government. We announce that only the government elected through clean votes will come to power."
The Afghan Independent Election Commission released preliminary election results yesterday showing former finance minister Ashraf Ghani well in the lead for the presidency but said no winner could be declared because millions of ballots were being audited for fraud.
Preliminary results from the June 14th runoff vote showed that Mr Ghani had about 4.5 million votes, or 56 per cent, while Mr Abdullah had 3.5 million votes, or 44 per cent, according to the commission. Turnout was more than 50 per cent.
That was a sharp turnaround from the first round of voting on April 5th when Mr Abdullah garnered the most votes with 46 per cent to Mr Ghani’s 31.6 per cent but he failed to get the majority needed to avoid a runoff vote.
Mr Abdullah has refused to accept any results from the second round until all fraudulent ballots are invalidated.
The election commission acknowledged that vote rigging had occurred and said ballots from about 7,000 more of the nearly 23,000 polling stations would be audited.
Mr Abdullah accused outgoing president Hamid Karzai, Mr Ghani and the election commission of colluding against him. "They ignored us and announced the fraudulent results," he said.
There were fears that Mr Abdullah could ignore the result and declare victory, something he hinted at during his speech.
He said: “People across the county call on us to announce our government and I can’t not say no to people’s wish, we don’t want civil war, we don’t want crisis. All of our lives we defended this country. We do not want crisis, we want national unity. We don’t want separation, we don’t want civil war.”
“We are the winner of the election without any doubt,” he said, but called on his supporters to give him a few days to find a solution.
Mr Kerry said during a visit to Tokyo that any action to seize power illegally in Afghanistan would lead to the end of US financial and security support.
He said suggestions of a “parallel government” in Afghanistan were a grave concern and added that he expected Afghan electoral institutions to conduct a full review of all reasonable allegations of irregularities. He said there was no justification for violence or threats of illegal action.
“Any action to take power by extra-legal means will cost Afghanistan the financial and security support of the United States and the international community,” Mr Kerry said.
Mr Abdullah said Mr Obama had called him to promise help “in cleaning up votes”.
AP