Guineans are voting to elect a president in the country's second democratic presidential election since independence in 1958.

Seven candidates are competing against President Alpha Conde, who is hoping to win a second term.

His main challenger, Cellou Dalein Diallo, has urged his supporters to vote despite the country's top court rejecting his plea for a delay.

The 2010 election saw a transition from military to civilian rule.

Since then Guinea has been badly hit by an Ebola outbreak and seen prices of key export bauxite - the raw material in aluminium - slump.

Opposition parties had wanted the vote postponed due to alleged anomalies in the country's electoral roll, but this has been rejected by the election commission.

Some of those trying to vote early on Sunday complained that voting materials were not ready.

At least three people have been killed in pre-election violence.

Mr Conde is favourite to win the election but a second round of voting is likely.

African Union and European Union observers are monitoring the election. Polls opened at 07:00 GMT and are due to close at 18:00 GMT.