The report was released more than three months after the incident at the Letpadaung copper mine.

However, the investigation commission – appointed by President Thein Sein and chaired by opposition leader Aung San Suu Kyi – also recommended the Chinese-backed project continue.

Opponents say the joint venture between China's Wan Bao mining company and a Burmese military conglomerate causes en-vironmental, social and health problems. They want it halted and are demanding punishment for those who hurt peaceful protesters.

Authorities said they used water cannon, tear gas and smoke grenades to break up the 11-day occupation of the mine last November, but protesters said burns were caused by incendiary devices and described fire balls shot at them during the night-time raid on their encampment.

A separate report released last month by a lawyers' network and a human rights group said police dispersed the protesters by using white phosphorous, an incendiary agent used to create smoke screens.

Yesterday's report did not specifically mention white phosphorus, saying only that smoke bombs containing phosphorous were used. The report said the smoke bombs do not usually create a flame but phosphorus can sometimes burn flammable materials within an eight-metre radius.

The commission recommended police receive riot-control training but added scrapping the mine could create tension with China and discourage investment.