Thousands of opposition supporters have held a peaceful demonstration in the Guinean capital to call for a free and fair legislative poll in May.

Carrying signs reading "Down with Guinean " and "Yes to a Free and Transparent Election," the demonstrators marched in the capital Conakry on Monday to demand a graft-free parliamentary election.

"The people have come out to say no to dictatorship, no to attempts to organize electoral fraud, and to demand free and fair elections," Mouctar Diallo, an opposition party leader, told journalists in Conakry.

The election should have taken place in 2011 but was repeatedly delayed until Guinea's electoral commission CENI announced in December 2012 that the legislative vote would go ahead this year.

The delays have deepened a political deadlock and led to intermittent violence in the country. In April, 2012, 20 people were injured in clashes with police during an opposition protest. In another such incident in December 2011, one person died and a number were injured.

The parliamentary election, slated for May 12, is intended to be the last stage in the mineral-rich West African nation's transition to civilian rule after a military coup in 2008.