One of 14 conditions is that Trump Doonbeg firm, TIGL Ireland Enterprises, must submit a management plan for the vertigo angustior snail before work can start.

This is because the snail is now in danger of extinction.

However, Friends of the Irish Environment (FIE) said it is worried that while such a management plan to save the snail might be provided to Clare County Council, it will not be made public before work starts.

While FIE has not appealed against the plans, it has lodged a so-called observational appeal with An Coimisiún Pleanála - which is handling an appeal against the permission granted in February - making it clear that it would like the management plan made public.

“Leaving crucial mitigation and monitoring to be agreed ‘behind closed doors’ is incompatible with EU environmental law and Ireland’s Aarhus obligations.

“FIE is calling for management and drainage plans to be published in advance, with an opportunity for public comment.

“If An Coimisiún Pleanála signs off on permissions that depend on unpublished management plans for a protected species already in terminal decline, FIE has told the Coimisiún it is prepared to test that decision again in the Courts," the environmental group said.

FIE's challenge to the original planning application in 2000 secured a requirement that the rare snail be protected.

As a result, its population rose to over a million, and Doonbeg became the most important site in Ireland for the species.

However, since the US president’s firm acquired the resort in 2014, its population has been in terminal decline.

In March, it was reported that plans to build the new ballroom had been halted after a sole objector from Longford had appealed against the development.

Liam Madden of Convent Rd, Longford, had lodged appeals with An Coimiúsin Pleanála against two separate planning permissions granted by Clare County Council in February for the permanent ballroom and other upgrades at the west Clare resort.

In his appeal against the planned ballroom, Mr Madden urged An Coimiúsin Pleanála to “please refuse this nonsense”.