* Dozens wounded in running clashes
* Demonstrators say election preparations flawed
* Guinea is world's top bauxite supplier (Updates number of wounded in lead, paragraph 4)
By Saliou Samb
CONAKRY, Feb 27 (Reuters) - Guinea's security forces fired teargas at thousands of rock-throwing anti-government protesters in the seaside capital Conakry on Wednesday in clashes that wounded more than 50 people, witnesses and other sources said.
The violence in the West African state is a result of soaring tensions ahead of a parliamentary election the opposition says is being rigged by the administration of President Alpha Conde.
"We don't know how it started, but the security forces charged the crowd and fired teargas," said Ousmane Camara, a Conakry resident at the protest. Other witnesses said demonstrators were hurling rocks and chunks of concrete at police, and setting fire to tires.
A statement issued by Guinea's presidency said 23 members of the security forces had been injured in the initial clashes, including one who was in critical condition. It added that 28 civilians were hurt as well.
"The government deplores these incidents and calls for civility, a sense of responsibility and for the goodwill of the people," Damantang Albert Camara, a government spokesman, said in the press release.
Guinea's opposition coalition had called for widespread protests in Conakry after announcing last week it would boycott preparations for long-delayed legislative polls, claiming the run up to the vote was flawed.
The election set for May 12 is intended to be the last step in Guinea's transition to civilian rule after two years under a army junta following the death of long-time leader Lansana Conte in 2008.
President Alpha Conde won a 2010 presidential election in the world's top supplier of bauxite, the raw material in aluminium, but delays in the legislative vote have deepened a political deadlock and led to intermittent violence.
The opposition says the elections commission chose the poll date unilaterally and that two companies contracted to update voter rolls have skewed the lists in Conde's favour. They also want Guineans living abroad to be allowed to vote.
Thousands of people had participated in peaceful protests across Guinea last week in support of opposition demands. The parliamentary poll was originally due to be held in 2011 but has already been delayed four times.
Conde has promised prosperity to the former French colony's 10 million people, whose economy produces only about $1.50 per person per day despite a wealth of natural resources, including the world's largest untapped iron ore deposit.
The European Union, a major donor, warned in November that it needed a credible and detailed timeline for the election to unblock about 174 million euros ($229 million) in aid. (Additional reporting by Richard Valdmanis; Editing by Richard Valdmanis and Michael Roddy)