South Africa's police claim they were forced to open fire on striking miners with live rounds because they were charged by armed men and compelled to “defend themselves”, the national police chief said on Friday.

 Riah Phiyega said that 34 miners were killed on Thursday and another 78 wounded when her officers used “maximum force” near Marikana mine, owned by Lonmin, the London-listed company.

They did so when a gang of “heavily armed” miners rushed towards them, armed with firearms as well as clubs and machetes. “Police retreated and were forced to use maximum force to defend themselves,” said Ms Phiyega.

South Africans have been appalled by the violence, which summons memories of the apartheid era and has been compared with the Sharpeville massacre of 1960. But Ms Phiyega said: “This is no time for blaming, this is no time for finger-pointing. This is a time for us to mourn the sad and dark moment that we experienced as a country.

President Jacob Zuma has left a summit of African leaders and travelled back to South Africa. 

 Police were called in after thousands of miners gathered at Marikana, about 62 miles north-west of Johannesburg.

Images broadcast by private television station e.tv carried the sound of a barrage of automatic gunfire that ended with police officers shouting: "Cease fire!" By that time, bodies were lying in the dust, some pouring blood. Another image showed some miners, their eyes wide, looking in the distance at heavily armed police officers in riot gear.

It was a harrowing development in a country that had been seen as a model of stability since white rule ended with South Africa's first free elections in 1994. The shooting recalled images of white police firing at anti-apartheid protesters in the 1960s and 1970s, but in this case it was mostly black police firing at black mine workers.

Several commentators said members of the new union, the Association of Mineworkers and Construction Union (AMCU), had guns and other weapons and used them when the shooting began.

Joseph Mathunjwa, the union's president blamed Lonmin, the London-list company which runs the mine, and said the huge National Union of Mineworkers collaborated against the striking workers.