Colombia’s top administrative court ordered the suspension of operations at 15 fracking wells operated by coal miner Drummond on Dec. 13, because they are at a production stage prohibited by an earlier ruling.

In a move hailed by environmentalists, Colombia's Council of State, which is tasked with ruling on administrative matters, ordered the National Hydrocarbons Agency (ANH) and the mining ministry to oversee the suspension of certain operations at the La Loma field.

The court said Drummond was in violation of its moratorium on fracking. The court has ruled exploratory pilot projects can go ahead while it hears a larger case on the technique, but that the use of non-conventional methods to produce oil and gas remain prohibited.

Drummond, a long-time coal miner in the Andean country, is spearheading at least one of four pilot projects, which could bring in up to $5 billion in investments annually once they reach the production stage, according to industry leaders.

Fracking, or hydraulic fracturing, is not common in Colombia. While the oil industry has said fracking is key to boosting the country’s reserves and ensuring energy self-sufficiency, the technique faces stiff opposition from left-leaning lawmakers, community leaders and environmentalists.

Carlos Andres Santiago, of the Colombia Free of Fracking Alliance, told journalists in a message that the ruling affirmed production of hydrocarbons by fracking is off limits.

“This makes it clear that even if there is an open door to pilots because of the decision taken several months ago, the regulation remains suspended and no type of activity related to the exploration or exploitation of non-conventional deposits can be developed,” Santiago said.

Colombia produces about 860,000 barrels of oil per day and has reserves equivalent to around six years. Energy Minister Maria Fernanda Suarez has said fracking could help triple the country’s reserves.

A spokesperson for the mining ministry said it had no immediate comment on the ruling, while representatives from Drummond did not immediately respond to a request for comment.

The ANH directed inquiries to the ministry.