Wicklow County Council has begun looking for illegally dumped waste at CRH's quarry complex in Blessington. Council officials visited the 680-acre site this week and the investigation is expected to take at least two weeks to complete.

Consultants working for the council will use sophisticated equipment to probe the site for buried waste. The method has already been used to examine illegal dump sites in Wicklow and Dublin. Roadstone Dublin, the CRH subsidiary which operates the Blessington complex, said yesterday it was co-operating with the council and was "absolutely confident that no significant quantities of household waste will be found". It added: "There is no physical evidence of significant dumping on Roadstone property at Blessington."

The company said yesterday that it believed the council's investigation was "part of a routine investigation into unauthorised dumping along the N81".

Sources close to Wicklow County Council said yesterday it had identified the Blessington site as a potential dump last December. The site came to the council's attention because of information gleaned from hauliers, who had been involved in illegal dumping elsewhere in Wicklow, including illegal dumps at Stephenson's Quarry and Whitestown near the Glen of Imaal and also Coolnamadra. Substantial amounts of hazardous waste have been found at these sites.

Roadstone said yesterday that "unfounded allegations relating to Roadstone's lands at Blessington are very damaging and entirely inaccurate and malicious. Roadstone does not permit any dumping of household waste on its lands." The discovery of significant amounts of waste on its Blessington site would be extremely embarrassing for CRH, which is one of Ireland's largest quoted companies and one of the world's leading building materials group. The company said yesterday that it had "an excellent environmental track record and took its environmental responsibilities very seriously. Cleaning up the site - should illegal dumping be unearthed - could also prove expensive. CRH's operations in Blessington were previously the subject of controversy in 1994 when Roadstone expanded its operation into the adjacent Glen Ding Wood without planning permission.

The Moriarty tribunal investigating political corruption has come under pressure to look at the 1992 purchase of the Glen Ding from the Government by CRH, which was not put out to tender.