Two people have been shot dead as Kenyan police tried to disperse opposition supporters marching from an airport alongside the convoy of opposition leader Raila Odinga, a Reuters witness says.
Kenyan police and supporters of the defeated opposition leader fought running battles along the main road to Nairobi's international airport.
Odinga has called for a "National Resistance Movement" to protest the outcome of a repeat presidential election, which was ordered by the Supreme Court after it annulled the results of an August poll over procedural irregularities.
Police fired into the air to disperse hundreds of people gathered outside Jomo Kenyatta International Airport who were waiting for Odinga to return from an overseas trip.
In what is seen as the last chance for legal scrutiny of the vote, the court will rule on Monday on cases that seek to nullify the rerun election. The political crisis has stirred fears for the stability of the east African nation, a regional hub for trade, diplomacy and security.
In Friday's violence, people threw stones at the police and threw up burning barricades on Mombasa Road, the highway that links Nairobi's downtown business district and the airport.
President Uhuru Kenyatta won a second, five-year term with 98 per cent of the vote in the repeat election after Odinga boycotted the contest. Only 39 per cent of registered voters took part.