An independent investigation has found that white phosphorus caused the severe burns that monks and other demonstrators suffered during a November crackdown by police on a protest against a mining project in north-western Myanmar, a lawyer said.

The crackdown left more than 100 people, mostly Buddhist monks, with burns that authorities said were caused by tear gas and smoke grenades.

But an analysis at a Bangkok laboratory found traces of white phosphorous in canisters that were left by police and later recovered by a group of lawyers at the Letpaduang copper mine, where officers broke up an 11-day occupation by protesters, lawyer Aung Thein said on Thursday.

White phosphorus is an incendiary agent generally used in war to create smoke screens. Guidance on its use against people is conflicting.

Mr. Aung Thein was not directly involved in the investigation, which was conducted privately by the lawyers, but he signed the report on the findings.

The report has been forwarded to the government-appointed panel headed by opposition leader Aung San Suu Kyi that investigated the incident.

Myanmar’s government spokesman declined to comment on the findings.

“Only the report of the Investigation Commission led by Daw Aung San Suu Kyi will be final,” presidential spokesman and Deputy Information Minister Ye Htut said in an email on Friday.

The mining project in Monywa is a joint venture between a military-controlled holding company and China’s Wanbao Mining Copper Ltd., a subsidiary of NORINCO, a Chinese weapons manufacturer.

Protesters wanted the project halted, saying it caused environmental, social and health problems.

The incident marked the biggest use of force against protesters in Myanmar since the reformist government of President Thein Sein took office in March 2011. — AP