Kenya's opposition leader Raila Odinga has said that he will not take part in the presidential election re-run slated for 17 October "without legal and constitutional guarantees".
Last week, the Supreme Court annulled August's election result saying the electoral commission (IEBC) had not followed the constitution.
Incumbent President Uhuru Kenyatta was declared the winner by the IEBC.
The court said a new election needs to be held by 31 October.
Speaking to journalists, Mr Odinga said that the fresh vote must held in an environment where everything that went wrong can be corrected.
"We know exactly what transpired in these last elections, we know what the IEBC did and we know that if we were to go back there will be no different results and that's why will say there will be no elections on the 17 October," he said.
Mr Odinga's opposition Nasa alliance went to the Supreme Court to challenge President Kenyatta's win arguing that the results had been tampered with during transmission from the polling stations.
They alleged that someone gained access to the IEBC's computer servers to tweak the results in favour of Mr Kenyatta.
The court found that, among other things, the IEBC had committed "illegalities" in the transmission of results. But as it has not released its full ruling it is still not clear exactly what went wrong.
The Supreme Court said on Friday that it would make its full ruling public within 21 days.
Mr Odinga wants the IEBC to strictly follow the constitution's guidance on conducting elections.
He also wants some of the commissioners to be sacked, alleging that they are partisan, and he is pushing for access to IEBC's electronic voting and result transmission system.
Mr Odinga criticised the IEBC for announcing the new election date saying that opposition parties had not been consulted.
Nasa sent a letter to the IEBC arguing that the date for the fresh election "should be a product of consultation with concerned parties and not a unilateral decision".
The opposition leader alleged that the election date was set by the governing Jubilee Party.
Mr Odinga also faulted the IEBC for saying that the new election will just be between him and Mr Kenyatta. There were eight candidates on the ballot paper in August.
"The entire election was cancelled by the Supreme Court," he said. "So it means that you do a repeat of the presidential elections afresh."
For his part, President Kenyatta said last Friday that while he respected the court's annulment of the election he disagreed with the decision.
Speaking to supporters later that day, at an impromptu rally in the capital, Nairobi, he described Chief Justice David Maraga as a "crook". On Saturday he vowed to "fix" the Supreme Court if he was re-elected.