Polls opened in Kenya early Wednesday as the nation votes in a referendum on a new constitution, part of the reform process aimed at avoiding a repeat of the violence that followed December 2007's elections, dpa reported.
The referendum is the first national vote since more than 1,300 people died in the tribal clashes that followed those disputed presidential elections.
Some 64,000 security officers have been deployed around the country in case of trouble, with particular focus on the Rift Valley, where rival tribes set about each other with machetes and bows and arrows during the post-election violence.
The run-up to the vote has been generally peaceful, although grenade attacks at a rally opposing the constitution killed at least five people at a park in central Nairobi in June. Nobody has been charged in connection with the blasts.
Just under 12.5 million Kenyans are registered to vote in 27,689 polling stations, which opened at 0600 (0300GMT) and close at 1700.
Opinion polls have shown that around 60 per cent of registered voters are likely to back the constitution, which would replace the document created after Kenya gained independence from Britain in 1963.
The constitution aims to peg back the power of the president through establishing a two-tier parliament, decentralizing power and introducing a host of other changes.
Both President Mwai Kibaki and Prime Minister Raila Odinga - the two men who were at loggerheads in 2007 - are backing the constitution, reducing the risk of trouble between their Kikuyu and Luo tribes and their allies.
However, opposition by the church over clauses on abortion and Muslim courts has created a significant opposition to the constitution.
Political leaders from the Kalenjin tribe have also backed a 'no' vote, often playing up on the touchy issue of land reform, and there are fears this could lead to a repeat of clashes between Kalenjins and Kikuyus in the Rift Valley.