Allan Wilson said his comment was not meant to be taken literally

Allan Wilson, the Labour MSP for Cunninghame North, made the comment during a Holyrood energy debate.

He said it was a metaphor and not a literal remark, but later apologised. Presiding Officer George Reid warned against the use of such language.

Nationalists and the Greens said Mr Wilson's comments were inappropriate.

Mr Wilson described the recent discussions between the Greens and the SNP as "the environmentalists on one hand and the environmental cowards on the other hand".

He added: "I would put it to you actually that the relationship, such as it is, the love affair, as it was called, or a flirtation, as Patrick Harvie called (it), is nothing less than attempted rape by the Nationalists."

SNP energy spokesman Richard Lochhead, who spoke during the debate, said: "This was a wholly inappropriate and offensive comment.

"Allan Wilson should think twice before he makes cheap, throwaway remarks of this nature."

I would have thought even the dimmest Nationalist would have worked out that it wasn't a literal reference Allan Wilson Deputy Enterprise Minister

A Scottish Green Party spokesman said: "Mr Wilson should apologise, not to us, but to people who have been the victims of rape.

"It's not a fit subject for trivial jokes and it's appalling that a member of the executive should use such language."

Mr Wilson initially denied his comments were unacceptable.

He said: "I would have thought even the dimmest Nationalist would have worked out that it wasn't a literal reference. It was a metaphor."

However, he later apologised to MSPs - an apology accepted by Holyrood's presiding officer.