A HOLYROOD independence referendum runs the risk of being unlawful as there is a "strong constitutional case" for Westminster to hold the poll, a law expert has claimed.

Professor Adam Tomkins told the Commons Scottish Affairs Committee that, if the Scottish Parliament pushed through a Bill in Edinburgh, it could be challenged by UK Government ministers and end up in the Supreme Court.

Mr Tomkins, the John Millar Professor of Public Law at Glasgow University, stated: “Scottish Ministers do not speak for Scotland generally, either in law or in fact. In law, they speak for Scotland on devolved matters. The extraordinary electoral victory of the Scottish National Party must not be allowed to obscure this.

“Winning a Scottish parliamentary election entitles a party to govern subject to the rule of law. It does not entitle a party to seek to rule in a manner that disregards the legal limits to its powers.”

Mr Tomkins said if Holyrood held the referendum “there is a very strong argument that the Act of the Scottish Parliament would be outwith competence and therefore ‘not law’ under section 29 of the Scotland Act 1998 and the Scottish Ministers would be acting outwith their devolved competence if they sought to exercise powers in pursuit of such an Act”.