The survey would become the seller's responsibility

The system was scheduled to start next month but the main surveyors body has said it has no confidence in it.

The Royal Institution of Chartered Surveyors (RICS) said many issues remained unresolved.

The Scottish Executive said it was committed to proceeding but the launch date depended on the RICS.

The problem affects about a third of buyers with an estimated �9m spent on reports which never lead to a sale.

The pilot scheme was due to begin in four Scottish cities in June. It will see the seller being responsible for commissioning a Stage 2, full structural survey, which would be made available to all prospective buyers

'Political anxiety'

But in a private letter to the Scottish Executive, RICS director Peter Miller said he believed there had been a great deal of "political anxiety" to get the scheme up and running.

The society had had no confidence in the system, which he said was being driven through with an "unseemly haste".

In a statement, Mr Miller said: "Although it is a pilot scheme it is dealing with real people, real properties and real money and there is a lasting responsibility to all those involved to get it right.

"We continue to work alongside the Scottish Executive diligently and with haste to resolve the outstanding issues.

"We have received a response from the minister and feel that it would not be productive to be drawn into further discussion at this time."

An executive spokesman said it would continue to talk to the RICS to try to resolve some of the issues.

He added that RICS had been part of a steering group which had been working on the single survey scheme for the last nine months.