The developer of a controversial coal mine in NSW plans to appeal a landmark decision that blocked the project in part on climate change grounds.

Gloucester Resources Ltd - which last month had its Rocky Hill open-cut mine near the Mid North Coast of NSW blocked in the Land and Environment Court - lodged its intention to appeal on March 5, the Supreme Court said.

Gloucester residents were jubilant after their win in the Land and Environment Court in Sydney against the proposed Rocky Hill open-cut coal mine in Gloucester a month ago - but the uncertainty has returned. Credit:Janie Barrett

A court spokeswoman said the miner has until May 8 to formally appeal, but added the period to make the appeal could be extended further.

Gloucester Resources confirmed it had filed a Notice of Intention to Appeal against the refusal of its coal mine. It declined to comment further.