In June, more than three million Guineans, 77 per cent of registered voters, took part in the presidential election [EPA]

Guinea's electoral commission chief has been sentenced to one year in prison for electoral fraud during June's presidential vote, just ten days before the contest goes to a run-off on September 19.

Ben Sekou Sylla, the president of the National Independent Electoral Commission (Ceni), and another official were convicted of vote-tampering on Friday.

Boubacar Bah, a senior prosecutor, said the pair had been sentenced to "one year in prison and a fine of two million Guinea francs [$350] each for electoral fraud".

The poor West African nation staged the first round of voting on June 27, with a second round run-off between Cellou Dalein Diallo, a former prime minister, and Alpha Conde, a veteran opposition figure, to follow later this month.

Diallo won 43.69 per cent of the first round ballots, with Conde taking 18.25 per cent of the vote. Diallo is expected to win the run-off vote.

Conde's Rally for the Guinean People (RPG) party accused Sylla and Boubacar Diallo, the head of planning at Ceni, of manipulating the voting records of the first round.

Earlier in the week, Boubacar Diallo said: "Alpha Conde knows he cannot win. So he is using his connections inside the army and inside the interim government to try to manipulate the outcome of the vote."

Some analysts have said that this latest development could derail a democratic transfer of power to the civilian population, in a nation currently led by the military following a coup in 2008.

In June, more than three million Guineans, 77 per cent of registered voters, took part in the presidential election.