Brazil’s far-right president, Jair Bolsonaro, unveiled a controversial bill on Wednesday that would allow commercial mining on protected indigenous lands, delivering on a campaign promise that has shocked tribal leaders and environmentalists.

The bill to regulate mining including oil and gas projects, as well as hydroelectric dams, on indigenous reservations for the first time, will be sent to congress this week. Brazil’s constitution currently does not rule out mining on reservations, but does not allow it because it has not been regulated.

“This is a big step forward, but it will face pressure from environmentalists,” Bolsonaro said in a speech.

Bolsonaro has long alleged that Brazil’s indigenous people occupy too much land – 13% of the country – and hinder economic development of untold mineral resources, from gold and diamonds to niobium and rare earths.

But leaders of most of Brazil’s 300 tribes oppose mining on their reservations and say that allowing commercial mining would undermine their communities and wipe out their cultures, which are already threatened by increasing invasions by illegal loggers and wildcat miners.

Environmentalists who see the indigenous communities as the best guardians of Brazil’s tropical forests warn that mining will speed up deforestation.

The proposal includes provisions to consult indigenous communities and would require congressional approval for any mining or hydroelectric power generation project. Government officials have said, however, that indigenous communities would not have the right to veto projects once authorized by congress.

Bolsonaro also separately plans to allow large-scale commercial agriculture on indigenous reservations, which is not permitted under current environmental laws.