International observers have urged candidates in Kenya's tense presidential elections to respect the outcome and resolve any poll disputes in court. Preliminary results by the electoral commission show incumbent President Uhuru Kenyatta leading the main challenger Raila Odinga 54% to 45% with more than 98% of polling stations reporting.
Odinga told CNN that he will not believe the final results when they are released.
His opposition party has maintained that the electoral commission's servers were hacked and the poll rigged in favour of Kenyatta. But Wafula Chebukati, chairman of the electoral commission, said Thursday while there was an attempt to tamper with the poll system, the hackers did not succeed.
Odinga's accusations prompted the European Union to urge losing sides to concede gracefully when final results are announced. The African Union, which also sent observers to the country, urged Kenyans to maintain calm as they await final results.
Kenya opposition claims election system hacked 01:37
"It is a sign of leadership and public service to be able to congratulate your opponent with grace as a normal and important part of democracy," Marietje Schaake, head of the EU mission, said in a statement Friday.
"And should there be a need to challenge any of the proceedings or outcomes, petitions through the courts are the avenue to take."
Schaake said the group assessed voting procedures and saw "no signs of centralized or localized manipulation."
Former US secretary of state, John Kerry, who served as an election observer for the Carter Center, said Thursday that while there were "little aberrations here and there," the election was not rigged.
He said the electoral commission is verifying electronic online reporting with the physical ballot forms from polling stations.
"If anything was electronically fiddled with, there is a way to go back and absolutely ascertain what happened in the polling station," he said. "So by paper ballots, there is a protection of each and every Kenyan's vote."