The Labour leader, Mr Dick Spring, has said the sale of State land in Co Wicklow should form part of the terms of reference for the next tribunal of inquiry into payments to politicians.

The Labour Party yesterday submitted an amendment to the Government's terms of reference to this effect.

The Green Party TD, Mr John Gormley, and Socialist Party TD, Mr Joe Higgins, will also table amendments, proposing that the sale of land at Glen Ding Wood, Blessington, in 1991, be specifically included in the tribunal's terms of reference.

The 147-acre site was sold privately by the Department of Energy to Roadstone Dublin Ltd, a subsidiary of Cement Roadstone Holdings, for £1.25 million.

The late Mr Des Traynor, Mr Charles Haughey's personal financier who controlled the Ansbacher accounts, was chairman of CRH at the time of the purchase.

The former Minister for the Environment, Mr Brendan Howlin, said the circumstances surrounding the sale of Glen Ding Woods had caused "significant disquiet, both locally and nationally" and demanded explanation.

Other Labour TDs - Mr Emmet Stagg (Kildare), Mr Tom my Broughan (Dublin North East) and Dr Pat Upton (Dublin North Central) - said the sale of Glen Ding merited examination by the tribunal.

Mr Stagg said: "I think it is well worthy of examination. It was sold without public tendering, which is most unusual, particularly when there was a application from another bidder at the time."

A statement issued by Framus Ltd, formerly National Concrete, which operated land adjacent to Glen Ding, said the land was sold for "substantially less than the market value of the property".

A study of the 147-acre site by the Geological Survey of Ireland in 1988 had indicated that it contained 24 million tonnes of sand and gravel.

An environmental impact study by CRH stated that the company would quarry 12 million tonnes from an 80-acre section. "CRH purchased 80 per cent of this land which suggests revenues of between £38 million and £57.6 million for that portion. That CRH were able to purchase this for £1.26 million is inexplicable," the statement said.

"The residual value, according to the valuation obtained by the Department of Agriculture, is in the region of £821,000, including timber reserves.

"This suggests a net cost to CRH of £439,000 for an asset worth between £38 million and £57.6 million (or approximately 2p per tonne for gravel worth £2/ £3 per tonne)."

The company stressed it was one of three companies operating sand and gravel operations out of the same reserve at the time of the sale and could have obtained access to Glen Ding. Roadstone Dublin Ltd said in a statement yesterday it "negotiated in good faith and followed Department of Energy guidelines at all times" in relation to the purchase.

It said the negotiations were conducted exclusively by senior exec utives of Roadstone, without any involvement whatsoever of people at CRH Group level.

"The exaggerated prices suggested by some are a nonsense. The paid price represents a very full valuation and was far higher than prices achieved for similar sites in the locality.

"Roadstone, by virtue of the fact that it already had a significant investment in the adjacent property, was something of a captive purchaser," the statement said.

"The acceptability of the valuation was acknowledged in a written answer to a Dail question on April 15th last by the former Agriculture Minister, Ivan Yates, who noted that a very full price was paid by the company to the State."