Indonesia has warned of legal action against a huge US-owned mine in Papua province, unless it does more to protect the environment.
Grasberg is one of the largest mines in the world
The Grasberg gold and copper mine has been the focus of protests by locals, who say it causes ecological damage but has little economic benefit for them.
Four policemen and a soldier were killed in riots at the mine last week.
The report came hours after a landslide at the mine killed three people. Mining can potentially trigger land slips.
Several other people were injured in the accident, in which tonnes of mud crashed through a cafeteria in the mine complex. All the victims were Indonesians, a mine spokesman said.
The government's warning to Freeport was sparked by an environmental audit carried out on behalf of the Indonesian administration.
It confirmed what activists have been saying for some time - that US mining giant Freeport needs to improve the management of the millions of tonnes of waste produced by the Grasberg mine, one of the largest in the world.
Environment Minister Rachmat Witoelar said there were fears that mounds of "tailings", as the waste is known, could become unstable, triggering landslides or flooding.
"Freeport must act not like it is a country within a country," Mr Witoelar said. "It must obey the law of the country and take into account the feelings of the people."
He said that mine operators would be given between "two and three years" to put improvements into effect, or his ministry would file a lawsuit.
The government recently settled a similar suit against mining firm Newmont, blamed for pollution at its mine on Sulawesi Island, with the company agreeing to pay $30m to fund environmental monitoring and community projects.
Freeport says it abides by all the necessary regulations and will work to implement the new recommendations.
A Freeport spokesman, Siddharta Moersjid, said on Thursday that the company "has the same objective as the Ministry of Environment, which is to minimise the impact of our mining operations to the environment".
The Grasberg mine has long been the focus of protests against Freeport, the Indonesian government, and the mine's security operation, run by the Indonesian police and military.
Last week, a protest escalated until five security officers were beaten by a mob. Four died straight away, and one later, from his injuries.