Campaigners fighting plans for 2,000 homes near a nationally protected wildlife area have yet to decide their next move after their latest legal action was rejected.

No Adastral New Town (NANT) says the project for BT’s Adastral Park site at Martlesham Heath will put at risk the Deben Special Protection Area for birds, one of the United Kingdom’s “jewels in the crown” of nature conservation.

NANT said it had been left disappointed after permission to appeal to the Supreme Court against Suffolk Coastal’s Local Plan was refused.

The group will now be discussing its next move with its legal team, with possibly the European Courts the only option left open.

A spokeswoman for NANT said: “We have not yet been told why and so we await the reasons with interest.

“We will then decide what if anything we will do further after that.

“It has already been established in the High Court that Suffolk Coastal’s process of selecting the BT Adastral Park site was unlawful.

“By the time the matter reached the Court of Appeal, the council accepted that the ‘consultation’ to double the number of houses on the BT site to 2,000 was also unlawful.

“However, the courts found that the council ‘saved’ itself by carrying out a further consultation, which is said to have ‘cured’ the earlier illegality, but we do not see how that squares with common sense and what we are advised are established legal principles.”

NANT has questioned how the such a crucial decision was “cured” without the necessary evidence base and all the issues being re-examined from scratch.

Suffolk Coastal has welcomed the Supreme Court’s refusal to hear a fresh appeal and said hopefully this would now leave the way clear for the authority to push ahead with the implementation of its local plan – creating much-needed new homes and jobs across the district.

The council has had an application on the table for six years for up to 60,000sq m of extra employment space in an innovation park with linked university provision, 2,000 homes, a mixed-use local centre, a school, a hotel, an energy centre, a public park and other areas of public open space, plus other community facilities at Adastral Park.

There would also be major changes to the road network, and an upgrading of the A12 alongside the site with new lanes and traffic lights.