* Odinga contesting Kenyatta's presidential poll win
* He has urged supporters not to resort to violence
* Kenya determined to avoid repeat of 2007/8 unrest
* Case a test of reformed judiciary's credentials
Allies of Kenya's defeated presidential contender Raila Odinga filed a petition on Tuesday asking the High Court to compel the electoral commission and mobile operator Safaricom to release documents to bolster their claim the vote was stolen.
Uhuru Kenyatta, indicted for crimes against humanity by the International Criminal Court (ICC), was declared the winner in a tightly contested election, which passed largely peacefully without a repeat of the violence that erupted after the last election in 2007, in which at least 1,200 people were killed.
Odinga, Kenya's prime minister, has so far refused to concede defeat. He says he will appeal to nullify Kenyatta's victory on grounds of fraud, in what will be the first major substantive case for a new Supreme Court formed under a constitution adopted in 2010 referendum.
Safaricom ran a mobile network that was used to transmit provisional results, until the election commission's servers seized up and the commission switched to manual transmission.
Kenyatta, one of Africa's richest men and son of Kenya's founding president Jomo Kenyatta, managed narrowly to avoid a second round by winning 8,100 votes more than the 50 percent needed to be declared the winner outright.
Odinga's supporters say Safaricom documents could help show some of those votes were fraudulent, forcing a second round.
He has told his supporters to shun violence, and so far there has been no unrest in flashpoint areas, such as Nairobi's Kibera slum, which Odinga represents in parliament, and Kisumu, a western city that is a bastion of his support.
"Even though the election was stolen, we don't want violence. We're filing a petition in court and we've enough evidence," Odinga told a rally in Kibera.
Odinga's Coalition for Reforms and Democracy (CORD) has up to seven days from Monday to file its case against the electoral commission. The court has 14 days to rule, which could delay the planned March 26 inauguration of Kenyatta.
Eliud Owalo, Odinga's campaign manager, said the court had agreed to hear the petition over the documents on Wednesday. He was seeking forms indicating the number of ballots cast in all polling stations countrywide, the register of all voters and details about the failed electronic vote counting technology.
"We already have massive evidence for our case, in addition to what we are seeking," Owalo told Reuters. "We have a case that will stand the test of time."
"FREE AND FAIR"
James Oswago, the chief executive officer of the Independent Electoral and Boundaries Commission (IEBC) repeated that the vote was free and fair, and said the commission was ready for any legal scrutiny. International observers have also said it was a broadly credible election.
Nzioka Waita, Safaricom's director of corporate affairs, declined to comment because the matter was in court. Safaricom has previously said its systems were not to blame for the technological problems during the vote count.
In his acceptance speech on Saturday, Kenyatta said the electoral process could be made more refined and efficient in future, but declared it "free and fair".
Kenyatta denies charges that he played a role in the wave of tribal killings that followed the disputed 2007 election, and says he will clear his name at his trial, set to begin in July at the International Criminal Court in the Hague.
His indictment complicates relations with Western capitals, who have said they would limit dealings with him.
Whether the Supreme Court can deliver a swift and credible resolution of the election dispute would impact the public's confidence in on-going reforms in the judiciary. Chief Justice Willy Mutunga has promised to deal with any election petitions in a fair, speedy and transparent manner.
"It would be a test. It is a difficult case and indeed the first major case to be determined by the Supreme court," said George Kegoro, executive director of the Kenyan International Commission of Jurists, a legal think-tank.
Kenya's stock market, where foreigners have been returning, has risen after a peaceful vote outcome, while the shilling has firmed against the dollar, although investors are concerned by the impact of Odinga's case.