The Edinburgh Airport rail link, an enormously ambitious and much-debated scheme with a £650 million price tag, is to have its projected costs scrutinised by Mr Robert Black Scotland's Auditor General. Mr Black will cast an eye over the cost projections before any ultimate decision is taken to either cancel or proceed with the project by the end of June.

In its pre-election manifesto the Scottish National Party (SNP) stated that it would abandon the rail link scheme as well as the trams project in Edinburgh, at least as the plans currently stand, but this approach brings to bear certain pressures for the SNP in as much as they are aware that the majority of MPs favour keeping both schemes alive. The SNP is savvy enough to realise that they would lose a parliamentary vote on the matter.

Mr John Swinney, the SNP's Finance Secretary has called upon the Auditor General to carry out brief evaluation by looking at " the process used to assess costs and risks to delivery" together with "the approach, the methodology and scope of the assessment used to identify costs."

The main concern expressed by SNP First Minister, Mr Alex Salmond, is the scope of the government's necessary financial promises to Edinburgh Airport's operator, BAA, to be granted a permit to tunnel under the runway.

Airport International's UK Correspondent.