Nairobi — Raila Odinga's Spokesman Prof. Makau Mutua now says the battle for the August presidential election won by William Ruto is still on.

Mutua said Odinga has never conceded and declared that the battle is still on.

"No one should imagine that the Kenyan presidential election is over we've never conceded anything. Stay tuned," he tweeted without elaborating.

The surpise sentiments follows a challenge filed at the East African Court of Justice by Raila's running mate Martha Karua.

Odinga lost to Ruto in a narrow victory which he challenged at the Supreme Court which dismissed the case for lack of evidence.

In Karua's petition at the Arusha, Tanzania-based court, she accused the Kenyan court of undermining "the rule of law by violating the right to a fair trial".

In the petition filed on Thursday, Karua, who is one of Kenya's best-known lawyers, urged the regional court to order Kenyan authorities to conduct "transparent, independent, and professional investigations into all (the) violations" allegedly committed by the election commission and the country's top court.

But the Supreme Court delivered a unanimous verdict in favour of Ruto, saying there was no evidence to back Odinga's claims.

Observers had feared that the disputed outcome could fuel violence in a country with a history of post-poll unrest, but voting day passed off peacefully.

The East African Court of Justice came into force in 2001 to ensure adherence to the laws establishing the seven-nation East African Community bloc, made up of Burundi, Kenya, Rwanda, South Sudan, Tanzania, the Democratic Republic of Congo and Uganda.

No Kenyan presidential election result has ever gone uncontested, with Odinga alleging fraud and hacking of the election commission's servers.