Nairobi/Conakry, Guinea  - Guinea's junta has called for a unity government in the wake of a crackdown by security forces that a local rights group says killed at least 157 people at an opposition rally.

A communique from the ruling military council, broadcast on state television and radio late Wednesday, called for the unity government and for a United Nations-backed investigation into the massacre.

The junta also said it wants to appoint an African leader to mediate between the military leadership and opposition parties.

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

The official death toll has been put at 57, but the Guinean Organization for the Defence of Human Rights says it counted 157 bodies and over 1,200 injured.

Witnesses and medical personnel told New York-based Human Rights Watch that many bodies were riddled with bullet holes, while others bore stab wounds from knives and bayonets.

They also said that troops sexually assaulted female protestors during the crackdown.

The junta claimed most people died in a stampede, although Camara admitted that some soldiers had lost control.

The UN commissioner for human rights welcomed calls 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.

Opposition leaders, who Camara said were to blame for the massacre by taking their supporters to a banned rally, had yet to react to the junta's offer.

Further opposition rallies have been banned.

The junta faced widespread international condemnation in the wake of the bloodbath.

The African Union, which has already suspended Guinea, has given Camara until mid-October to rule himself out of the presidential race or face sanctions being slapped on his regime.

Guinea's former colonial master France has withdrawn military cooperation and the European Union is withholding millions of euros in aid.

However, mineral-rich Guinea is the world's largest bauxite exporter and rakes in huge amounts of cash from foreign mining companies.

Camara, who received his basic military training in Germany, 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)