An Taisce, The National Trust for Ireland, which frequently objects to supermarket developments, has admitted it received €25,000 (£20,600) in corporate funding from Tesco.

Critics claim the Tesco donation, disclosed in An Taisce's annual report, was a serious conflict of interest. They are now calling on environment minister John Gormley to order An Taisce to be 'stood down' until an investigation into its funding had taken place.

As a heritage body, An Taisce has special status in the Irish planning system, with local authorities required to notify it of all proposed developments that could impact on the environment. It frequently ­objects to high-profile projects, going to the Planning Appeals Board and, in the process, has been accused of being elitist and anti-development.

An Taisce insisted the money was given without conditions and that, since receiving the donation, it had objected to developments involving Tesco and would continue to do so when it felt planning rules had been broken.

An Taisce heritage officer Ian Lumley added that the Tesco cheque was unsolicited and regarded as a one-off. It arrived, he said, following lengthy talks with the company on its new eco-store in Tramore, Co Waterford, and had been used for environmental work. "Our planning function is entirely funded by our membership," he said.

Since receiving the funds, Lumley added, An Taisce had successfully ­objected to developments involving Tesco at Carrickmacross, County Monaghan; Bantry, County Cork; and Tuam in County Galway. It had also objected to store plans by Lidl.

Despite the insistence, long-time heritage campaigner Vincent Salafia said it was "a matter of serious concern that An Taisce is receiving money from groups regularly seeking planning permission". "We feel there is a definite conflict of interest, with An Taisce taking money from corporate and government sources," he added.

Tesco declined to comment.