Nairobi/Conakry, Guinea  - Guinea's junta has announced it is to set up a commission to probe a massacre by security forces at an opposition rally, reports said Wednesday.

Guinea's security forces last month opened fire on an estimated 50,000 demonstrators at a stadium in the capital Conakry as they protested against junta leader Captain Moussa Dadis Camara's rumoured decision to run for president.

A local human rights group says 157 people died, while the government puts the figure at 57.

The junta on Wednesday night announced on state television that it wanted political parties, unions, civil society and the military to contribute members to the commission, a local journalist told the BBC.

The UN commissioner for human rights had called for an inquiry, but said it must be impartial.

"It is essential that such an inquiry is both independent and impartial so that all those responsible for carrying out summary executions, rapes and other human rights violations are brought to justice," Navi Pillay said in a statement.

It is not clear if opposition parties, who earlier rejected the junta's plans to bring in an African mediator, will provide representatives to the commission.

The junta faced widespread international condemnation in the wake of the bloodbath, during which witnesses said troops shot, stabbed and sexually assaulted protestors.

Camara was an unknown until he took control of the West African nation in December, following the death of strongman president Lansana Conte.

While Camara initially said he would not attempt to rule in the long-term, he is widely expected to announce he will run as a candidate in January 2010's presidential elections.

Analysts say that further opposition rallies and consequent violence are likely should Camara run. (dpa)