Chad has suspended all operations of a Chinese state-run oil firm for causing environmental damage, Chad's oil minister has told the BBC.
Djerassem Le Bemadjiel said the China National Petroleum Corporation (CNPC) was to blame for an oil spill in several sites near a forest.
He said the situation was "intolerable" but did not make it clear how long the suspension would last.
The company also runs an oil refinery in the capital, N'Djamena.
Chad became an oil-producing nation in 2003 with the completion of a $4bn (£2.6bn) pipeline linking its oilfields to terminals on the Atlantic coast.
The oil minister took the decision after officials visited Koudalwa, some 200km (125 miles) south of N'Djamena, where CNPC was exploring for oil, the AFP news agency reports.
"It's a very serious situation, it's intolerable," Mr Le Bemadjiel told the BBC French Service, describing how trees had been destroyed.
He said such violations were a crime, adding: "In the oil sector you don't do this."
The minister told AFP that the Chinese exploration unit had dug huge trenches and let oil flow into them, and then had it removed by local workers without protective gear.
Managers at the company would be held responsible for the violations, he told AFP.
The BBC's former Chad correspondent Celeste Hicks says the CNPC refinery, Djermaya, deals with about 15,000 barrels of oil a day from its operations in Koudalwa, producing fuel for the local market.
It has been closed twice before in disputes between the government and CNPC over pricing, she says.