Scottish manufacturers would benefit from returning the European Union to its free-market origins, the new head of the industry group Scottish Engineering has said.

In his first intervention on public policy since assuming leadership of the 350-member body at the start of the year, Bryan Buchan criticised the "evolution" of the original EU, and the "expansion of multiple layers of bureaucracy producing legislation which is counter-productive and inhibits business growth".

A former managing director of US optical giant Bausch & Lomb's Livingston plant, Buchan warned withdrawal from the EU, an option Prime Minister David Cameron has pledged to include in a referendum, would damage Scots business.

Buchan said: "It would certainly be extremely detrimental to Scottish companies to have such free access to European markets cut off."

However, he effectively backed the PM's strategy of trying to win back control of social legislation. "The points currently being made in relation to the evolution of the European Union from its origins as a free market are very valid," he said.

Buchan suggested manufacturers in other countries were more able to get around social legislation.

He cited an alleged Dutch practice of designating all staff as "autonomous decision makers" exempting them from working restrictions, and an alleged Danish practice of sub-dividing employment contracts so restrictions on workers' time are multiplied by separate "jobs".

Buchan also said the time-frame of the EU vote is a layer of uncertainty on top of that caused by the impending independence referendum.

"Manufacturing and engineering, by their natures, require some degree of stability in order to plan ahead in terms of raw materials, capital equipment and personnel. It's quite simple. Uncertainty inhibits investment," he said.