Outgoing Kenyan Prime Minister Raila Odinga on Saturday lodged a petition with the country's top court to challenge the outcome of the presidential election that saw him defeated by his rival Uhuru Kenyatta.
The move will be seen as a test of democracy in Kenya, which was rocked by bloody violence after the last disputed polls in 2007, when more than 1,100 were killed and hundreds of thousands were displaced.
Odinga's Coalition for Reform and Democracy (CORD) claims the poll was marred by irregularities including changes to the voter register and inflated numbers of registered voters. They also accused the electoral commission of using "poorly selected, designed" electronic equipment to transmit the results.
With the petition, Odinga is asking the court "to set aside the results of the presidential election as announced on March 9 and the declaration of Uhuru Kenyatta as president-elect... and declare null and void the whole electoral process," according to a CORD statement.
The party filed the suit at the Supreme Court in the capital Nairobi after Odinga spoke to supporters and reporters outside his offices.
"I have no hesitation whatsoever in lawfully challenging the election outcome," he said.
"To do otherwise would be a betrayal of the new constitution and therefore of everything that Kenyans hold dear," Odinga said.
Earlier on Saturday, police used tear gas to disperse around 100 people demonstrating in favour of Odinga at the court.
An AFP photographer saw one young man bleeding from a wound to the forehead. Bystanders said he had been struck by a tear gas cannister.
Kalonzo Musyoka, Odinga's running mate in the March 4 election, accused the police of being heavy-handed and said Kenyans had simply "been trying to exercise their constitutional right to freedom of movement."
But he called on party supporters to remain calm.
"We call on all supporters to give the rule of law a chance. We remain confident justice will be done," he said.
Kenyatta, who avoided a second-round run-off vote by the slimmest of margins to win a majority with just 50.07 percent, beat Odinga -- his closest rival -- by more than 800,000 votes.
Odinga won 43.31 percent of the votes in his third failed attempt at the top job. He said he would abide by the decision of the court and urged Kenyatta to do likewise.
"I have repeatedly indicated my commitment to respect and abide by the Supreme Court ruling. I invite my brother Uhuru to publically do the same," he said.
The Supreme Court has 14 days in which to hand down a ruling.