A parliamentary report on Tuesday revealed the use of phosphorus-laden smoke bombs to crack down on protesters at a Chinese-backed copper mine in northern Myanmar last year.

The government-commissioned report criticized police over the use of phosphorus to disperse protesters at the Monywa copper mine in the harshest clampdown yet, according to AFP.

Police used “unnecessary forceful means” against the protesters “without knowing what their effect would be,” the report said.

The incident left civilians and more than 100 monks injured. Many of the injured had severe burns, sparking further protests and leading to an official apology to senior clerics for the violent crackdown.

However, the probe stopped short of shutting down the joint venture between Chinese firm Wanbao and military-owned Myanmar Economic Holding.

The mine should “not be stopped”, the report said, because that could discourage potential foreign investment and would upset relations with China, although the report also conceded the $997 million joint venture only brought “slight” benefits to the nation.

Suu Kyi is due to visit the mine in Monywa and a number of nearby villages on Wednesday, a member of her security staff told AFP. But she could face a cold reception from local residents who protested against the project over environmental threats and land-grabbing issues.

“We will go on until the copper mine project is closed down,” activist Thwe Thwe Win told AFP.