Colombia's top administrative court on Sept. 17 clarified that a moratorium on fracking it upheld last week does not prevent "investigative" pilot projects, surprising both oil companies and environmental activists.

Magistrates from the Council of State, which rules on administrative matters, had maintained a temporary moratorium on the use of hydraulic fracturing, known as fracking, amid ongoing arguments in a wider case about the technique.

"The court advises that the reach of this decision does not impede the development of comprehensive investigative pilot projects ... made by the expert commission convened by the national government," the council's president, Lucy Bermudez, said in a statement.

An expert commission in February recommended that three pilot projects be strictly monitored before the country decides whether non-conventional techniques for extracting oil and gas can be widely used.

Regulations for development of non-conventional deposits were suspended in Colombia late last year as part of the lawsuit, filed against the energy ministry by an environmental lawyer.

State-run oil company Ecopetrol, which is a co-defendant in the suit and had asked the court to lift the suspension, saw its request to start a pilot project paused in July pending the court's decision.

The company has said it is looking to spend $500 million on exploring unconventional deposits over the next three years.

Ecopetrol said it was continuing basic preparations and community contact, as the expert commission recommended.

Any projects will probably take months to begin.

Industry groups last week expressed disappointment in the decision to uphold the moratorium, with the Colombia Petroleum Association warning it could affect investor confidence and put Colombia's fiscal sustainability at risk.

Anti-fracking group the Alliance for a Colombia Free of Fracking had hailed the ruling.

A representative from the alliance said Tuesday that fracking would not be allowed because of the lack of regulations.

The energy ministry, which has said fracking could nearly triple the country's oil and gas reserves, did not immediately respond to a request for comment.

Although there is no law against fracking, which breaks up rock formations with pressurized liquid and is not yet widely used in Colombia, the government says regulations are needed.

Fracking is credited for booming oil and gas production in the United States, but environmentalists have blamed it for water pollution and earthquakes.

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