NAIROBI - Kenya's defeated presidential contender Raila Odinga rejected the election outcome on Saturday and said he would challenge it in court, but called on his supporters to avoid violence.

His rival Uhuru Kenyatta, indicted for crimes against humanity, was declared winner of the election with a tiny margin, just enough to avoid a run-off.

Odinga's camp had said during tallying that the ballot count was deeply flawed and called for it to be halted. But Odinga asked his supporters not to resort to violence.

Odinga said there was rampant illegality in the electoral process and that "democracy was on trial in Kenya".

"We will therefore shortly move to court to challenge the outcome that the IEBC (Independent Electoral and Boundaries Commission) announced a few hours ago," Odinga told a news conference, adding he would accept the ruling of the court.

"Any violence now could destroy this nation forever, but it would not serve anyone's interests," he said.

Odinga said he would have conceded if the vote was fair.