Kenya's outgoing President Uhuru Kenyatta pledged Thursday that there would be a smooth transition of power after a hotly disputed election whose outcome could be challenged in court.

At a meeting with Kenyan religious leaders on Thursday, Kenyatta "assured them that the process of transition will be smooth", his office said in a statement.

Kenya's Deputy President William Ruto has won the presidential election, Wafula Chebukati, the chairman the Independent Electoral and Boundaries Commission (IEBC) announced on Monday evening. He narrowly beat his rival, Raila Odinga, taking 50.49 percent of the vote.

Odinga on Tuesday rejected the presidential election results announced by the electoral body Monday and vowed to pursue legal and constitutional means to overturn the declaration of the president-elect.

The outcome has also caused a friction within the Independent Electoral and Boundaries Commission (IEBC). Four of its seven commissioners have disowned the results and accused the body's head of acting outside the constitution.

Any challenge to the results must be lodged by next Monday afternoon with the Supreme Court which then has 14 days to issue a ruling. If it orders an annulment, a new vote must be held within 60 days.