A CONTROVERSIAL decision to ban the cultivation of GM crops in Scotland was not based on scientific evidence, Nicola Sturgeon has admitted.

The First Minister said the move, announced last month, took into account "potential wider economic ramifications" for the food and drink industry.

Her comments were described as "flabbergasting" by the Scottish Conservative MSP Murdo Fraser, who said they raised questions about the role of specialist scientific advisers attached to the Scottish Government.

The ban took Scotland's scientific community by surprise when it was announced by Rural Affairs Secretary Richard Lochhead.

Mr Lochhead argued it would protect the "clean, green" reputation of Scottish produce at home and abroad.

But in an open letter to the minister, around 30 organisations and research institutions, including the Royal Society of Edinburgh, the Roslin Institute and the European Academies Science Advisory Council voiced their concerns about the "negative impact" a ban could have.

They warned it risked "constraining Scotland's contribution to research and leaving Scotland without access to agricultural innovations which are making farming more sustainable elsewhere in the world."

It later emerged ministers were unable to consult the Scottish Government's chief scientific adviser because the post has lain vacant since last year.

Ms Sturgeon was drawn into the row last week when she failed to clarify whether Professor Louise Heathwaite, the lead scientific adviser to Mr Lochhead's rural affairs and environment department, had been consulted prior to the announcement.

Replying to a letter from Mr Fraser, she said the Scottish Government wished to take advantage of changes to EU rules allowing countries to opt out of growing GM crops that have been approved for cultivation.

She wrote: "The science and the decision on the suitability of a GM crop for a particular area are quite distinct.

"The decision that the Scottish Government took, therefore, was not one based on scientific considerations but, rather, one which took into account the potential wider economic ramifications that growing GM crops might have for Scotland."

She said Professor Heathwaite "was consulted on the scientific background that was made available to ministers prior to the decision." but added: "That was not the primary factor in reaching the conclusion."

She said Scottish food was "internationally valued" for being produced "under clean, green and natural conditions" and insisted the ban on growing GM crops in open fields would "not impact" on the work of research institutes in Scotland.

She added: "The Scottish Government remains committed to drawing on the very best science advice and expertise."

Mr Fraser said: "The SNP appears to be admitting this significant decision has not been made on scientific grounds.

"So if it hasn’t been made on scientific grounds, on what basis has it been made?

"People will conclude the ideology and dogma of the left is dictating key environmental and economic decisions – that is a flabbergasting state of affairs."

He added: "While this letter says the adviser was indeed informed, it doesn’t detail what the reaction was.

"Presumably, that omission tells its own story.

"No wonder the SNP cannot recruit a new chief scientist if this is the way they treat scientific advice."

Mr Lochhead was also asked what scientific evidence he considered prior to the ban.

But, responding to a parliamentary question from Labour's Drew Smith, he failed to cite a single example.

Scotland is a world leader in "bio-sciences," a field that includes genetically modified crops.

It is one of a select group of "growth sectors" identified in the Scottish Government's own economic strategy where Scotland enjoys an advantage over its competitors.