A London court denied a petition from environmental groups to halt construction on a hydroelectric dam in a rain forest in Belize, although the justices will hold a hearing in December to listen to arguments challenging the environmental approval of the project.

A judicial committee of the Privy Council refused to grant the injunction against Fortis Inc., the Canadian company set to build the Chalillo Dam, unless groups opposed to the construction posted a large bond to cover potential costs for the litigation.

But by ruling that it could grant an injunction in a civil case, the court set a precedent for civil rights.

Previously, stays were reserved for executions in death row cases. Environmental and other groups have opposed the dam, arguing that it would threaten rare and endangered animal species and questioning the legality of the permits obtained to build the project.

Fortis executives have insisted approval for the dam was obtained according to the law.

The Privy Council, which is the highest court of appeal for many Commonwealth  countries, also raised questions about a law passed recently in Belize designed to shield the Fortis project from the law.