Kenya's Deputy President William Ruto has won the presidential election, the electoral commission chairman announced on Monday evening.

The Independent Electoral and Boundaries Commission (IEBC) Chairman Wafula Chebukati said Ruto garnered 7176,141 votes, or 50.49 percent of the total votes cast ahead of veteran opposition leader Raila Odinga who garnered about 6942,930 votes, or 48.85 percent of the votes.

Immediately after the announcement of the presidential results, protests broke out in some parts of the country, mainly Odinga's strongholds in western Kenya, the capital Nairobi and the eastern part of the country.

Police in the western Kenyan city of Kisumu, some parts of Nairobi including Kibera and Mathare slums, engaged Odinga's supporters in running battles to protest the presidential results, alleging irregularities.

Nairobi's central business district had earlier been deserted as several shops were hurriedly closed amid traffic snarl-ups out of the city.

Ruto, who spoke soon after receiving a certificate to confirm his victory pledged to extend a hand of friendship to political rivals, unite the country and advance shared growth and prosperity.

"The people of Kenya have assigned us a responsibility to execute and I promise to run a transparent, open and democratic government that serves everyone fairly," said 55-year-old Ruto flanked by immediate family members and political allies.

The announcement was delayed amid scuffles and allegations of vote-rigging by Odinga's campaign.

Four of the seven members of the electoral commission were absent at the announcement.

"We cannot take ownership of the result that is going to be announced because of the opaque nature of this last phase of the general election," said ­Juliana Cherera, the IEBC vice chairperson.

Cherera said the institution had carried the election process in a fair manner until the final part of tallying the results.

She urged those aggrieved to challenge the results in court.