In February, Environment Minister Alex Attwood confirmed the granting of planning permission for the construction of the course, hotel and villa complex at Runkerry close to the Giants Causeway.

The 350 acre development called Bushmills Dunes, headed up by a US-based Northern Ireland businessman Dr Alistair Hanna, will include a championship links golf course, a five-star 120-bedroom hotel and 75 villas.

However, the conservation charity has confirmed to UTV that it is seeking leave for a judicial review of the decision.

The Trust said they had been left with "no option."

A statement read: "The National Trust has consistently opposed the planning application and in particular has expressed concern that the entire development is on land which is zoned in the draft Northern Area Plan as the distinctive landscape setting of the World Heritage Site in which no development should take place."

It continued: "This is based on a recommendation by UNESCO - the body responsible for World Heritage designations - that there should be a buffer zone to protect the special landscape surrounding the Causeway."

Mr Attwood described the charity's decision as "deeply disappointing."

He said the timing of the decision "raises questions for the National Trust about how it views itself."

Mr Attwood continued: "This Runkerry decision was taken by me only after a long time and after full consideration of planning, economic, environment, heritage and other issues.

"The decision went to great lengths in protecting the natural environment and heritage and I made sure that it did."

He said he would discuss this matter with Executive colleagues.

"I know that my disappointment is shared at a political level. I believe it will be shared by the general public."

Bushmills Dunes has also expressed their disappointment.

A statement said: "The development will provide a much-needed piece of world class tourism infrastructure on the North Antrim Coast. It not only has the strong support of the Northern Ireland Tourist Board, but also enjoys unanimous cross-party political support.

"We have been working in very close partnership with landowners and the Executive's environmental agencies for many years to ensure all protective measures are in place."

It said that "at a difficult time for the Northern Ireland economy, the provision of hundreds of jobs will also be delayed."

But James Orr, the NI Director of Friends of the Earth, said they welcomed the National Trust's decision.

"We absolutely welcome the courage of the National Trust in taking this very important step to preserve not just the Giant's Causeway but the only World Heritage Site in Northern Ireland."

He told UTV that he believed the Minister's decision overruled planning policies that protected "one of the jewels in our crown."

"Today, we think there is an opportunity for that decision to be reversed."