Guinea's government has promised an investigation into why members of the military opened fire on an opposition protest killing, by some accounts, more than 150 people.

Moussa Dadis Camara, Guinea's military leader, apologised for the violence and announced two days of national mourning to begin on Wednesday, but also banned any further "subversive" gatherings.

"Any mass gatherings which are of a subversive nature are banned," Camara said on television.

He urged Christian and Muslim authorities, as well as political and civic leaders and journalists, to "abstain from acts that disrupt public order".

He also asked for national prayers to be held on Friday and Sunday in memory of the dead.

Violent crackdown

A human rights group said that 157 people were killed and more than 1,000 injured when Camara's presidential guard fired on 50,000 pro-democracy demonstrators gathered at the main football stadium in Conakry, the capital on Monday.

Mouctar Diallo, an opposition activist, said he witnessed soldiers sexually assaulting women with rifle butts during the crackdown.

"I saw this myself," he said on Radio France International (RFI). "They were raping women publicly. Soldiers were shooting everywhere and I saw people fall."

He also said he had received further reports of rapes on Tuesday.

Sydia Toure, one of two former prime ministers injured at the protest, was reported by the AFP news agency as saying that the shootings were "a deliberate attempt" to eliminate the opposition.

Despite its planned investigation, the government continues to maintain that the protest was illegal.

It also claimed that far fewer people died than was reported.

A statement from the interior ministry disputed the rights group's figures, saying the death toll was 57 and only four of them were killed by bullets. The rest were trampled or died of asphyxiation, it said.

'Uncontrollable elements'

Camara says the "atrocities" were carried out by "uncontrollable elements in the military".

"Even I, as head of state in this very tense situation, cannot claim to be able to control those elements in the military."

"It's unfortunate, it's dramatic," Camara told RFI. "Very frankly speaking, I'm very sorry, very sorry."

The United Nations, African Union and European Union, and Canada have all expressed alarm over the killings.

The US government accused Guinea's security forces of "brazen and inappropriate" use of force against the protesters and called for the quick release of opposition leaders.

Ban Ki-moon, the UN secretary-general, deplored the "excessive use of force" and said he was "shocked by the loss of life, the high number of people injured and the destruction of property".

International condemnation

The African Union Commission, condemned the "indiscriminate firing on unarmed civilians", and urged Guinean officials to respect freedom of expression and assembly.

Guinea's membership of the AU was suspended after Camara seized power last year.

International powers have condemned the military use of 'excessive force' [AFP]

But his heavy-handed tactics were criticised after he authorised raids on the homes of well-known members of the dead president's inner circle, which he said were intended to recoup money and property stolen from the state.

His recent suggestion that he could stand for election in January, having previously said he would not run, is thought to have sparked the Conakry demonstration.

Some at the football stadium demonstration were reported as chanting: "We want true democracy."

France, Guinea's former colonial ruler, has called on the military government to "show responsibility and to listen to the Guinean people's legitimate aspiration to democratically choose their leaders".