Kenya: Demonstrators storm election commission
Odinga led hundreds of supporters in the protest outside the Nairobi offices of the Independent Electoral and Boundaries Commission (IEBC), an AFP reporter witnessed.
The runner-up in Kenya's last presidential election in 2013 accuses the commission of being biased towards President Uhuru Kenyatta and demanded that a new slate of commissioners be named ahead of the next election in August 2017.
The police fired warning shots and tear gas to disperse the demonstrators when they tried to break through police lines to reach the IEBC. There were no immediate reports of injuries.
Odinga was whisked to safety by his bodyguards.
The 71-year-old politician had given notice of his plans to "eject" the electoral commission's members in a speech at a rally in the capital on Sunday.
"We are not the only ones saying this. The church leaders have also spoken and said IEBC must be reconstituted, that is why we must go there tomorrow to eject them out of office."
Nairobi police chief Japheth Koome had warned ahead of the rally that only a few opposition representatives would be allowed into IEBC's offices to present their grievances.
Reacting to the criticisms levelled at the IEBC, spokesperson Andrew Limo said in a statement the commission was committed to taking the necessary steps "to ensure the next election will be free and flawless."
But "these preparations will suffer if the commission is subjected to frequent disruption, unfounded agitation, meddling and interference", he warned, vowing the commission would not be "intimidated".
Kenyatta beat Odinga by more than 800 000 votes to win the presidency in 2013.
Odinga and civil society groups accused the electoral commission of a series of irregularities that they said skewed the results.
The election nonetheless passed off peacefully for the most part, in contrast to the country's disputed 2007 elections which degenerated into fierce inter-ethnic violence that killed more than 1 100 people after Odinga's supporters challenged his defeat by Mwai Kibaki.
The next election in August 2017 is shaping up as a rematch of the 2013 election, with Odinga expected to try to unseat Kenyatta, 54.