James Kelly, MSP for Rutherglen and Labour spokesman for infrastructure, has written to Transport Minister Keith Brown for an explanation about delays to a study of potential public transport improvements for the airport. It was revealed this week independent consultants Aecom submitted about 12 best options in April, including a recommendation for a heavy rail link. The shortlist have yet to be made public as transport bosses are said to be unhappy rail is on the list.
They fear it would reignite controversy over the axing of the £210 million Glasgow Airport Rail Link project.
The study was commissioned last year by Glasgow Airport, Transport Scotland and Glasgow and Renfrewshire councils.
Mr Kelly said "That the delay is stopping the proposed options being costed is bad enough but I will be extremely disappointed if it emerges that the delay was a face saving measure from the Scottish Government."
Transport Scotland has denied delaying the report, which a spokesman said is "still being finalised".
A spokesman for Transport Scotland said: "We are one of a number of active participants in the work of the group and the initial appraisal report is currently being finalised. Partners will then take forward a detailed Appraisal Study with a view to publishing a final report early next year. The detailed appraisal will consider the cost benefit analysis of the shortlisted options along with other criteria as set out in the Scottish Transport Appraisal Guidance."