TORONTO -- Shares of Hudbay Minerals Inc. (HBM.TO) closed down more than 21 per cent on the Toronto Stock Exchange Thursday on news that a U.S. court had blocked development of a major copper mine.

The company says a U.S. federal judge in Arizona ruled that its nearly US$2-billion Rosemont project cannot proceed at this time after overturning an approval from the U.S. Forest Service.

The judge ruled the agency improperly evaluated and considered water use issues associated with the Rosemont Mine planned in the Santa Rita Mountains on part of the Coronado National Forest.

Conservation groups that challenged the project hailed the ruling, saying it recognized that the Forest Service failed to protect public land and resources.

Hudbay says it is "extremely disappointed" with the decision, believing the project conforms with federal laws and regulations, and will appeal.

The company's shares closed down $1.37, or 21.37 per cent, at $5.04 on the TSX.