Scottish ministers are making "stabs in the dark" in trying to boost the economy because official figures do not make sense, according to an economic report.

It suggests the new SNP administration may already have achieved its key goal for the next four years.

The intention of bringing the growth rate of the Scottish economy up to the British average is based on figures that show Scotland lagging badly.

But the research published yesterday by the Centre for Public Policy for Regions, based at Glasgow and Strathclyde universities, shows that gap could be a myth.

It argues the basis for those statistics is highly questionable.

Official statistics assume the Scottish hospitality and retail sectors have hardly grown over recent years, while parallel figures for England show retail up by 25% in eight years and hotel and catering by 33%.

Yet it is clear from living in Scotland that tourism, catering and shopping have been buoyant in the same way they have done well south of the border.

The report is a major challenge to the SNP administration, as it undermines the central political argument it has pursued - that Scotland is left trailing in the wake of the rest of the UK, and its economy should be faring much better.

As its core policy, the SNP wants to raise the average annual growth rate for Scotland over recent years.

Official statistics show that has been 2% between 1998 and 2006, while the UK average was 2.7%.

The research has been carried out by John McLaren and Professor Richard Harris. Mr McLaren has strong links to the Labour Party, though as an independent economist, Mr Salmond was keen to highlight a report he recently compiled showing Scotland's poor performance by international comparison.

Mr Harris said the implications were very serious, as unreliable data meant government could only make "stabs in the dark" about economic policies.

An executive source responded that growth figures have been "pretty clear and consistent, they paint a pretty devastating picture, and they've been the basis for John McLaren showing how bad things are in the past".