Scottish politicians have condemned a remark by the leader of one of Northern Ireland's main parties which appeared to compare the SNP and Irish terrorists.

Ulster Unionist leader Tom Elliott claimed in a column the party posed a greater threat to the Union "than the violence of the IRA".

Labour MSP Michael McMahon said the comments were "palpable nonsense and an insult to the common sense of the Scottish people".

Comparisons between the constitutional question in Scotland and the Troubles in Ireland "did not fit easily", he said. The row comes just days after Northern Irish politicians took exception to a remark by Alex Salmond which appeared to compare the move towards a Scottish independence referendum and Ireland's struggle before partition.

Mr Elliott, who leads the second-largest unionist party in Northern Ireland, wrote that the province had endured a "30-year terrorist campaign designed to break the will of the unionist people".

He wrote: "With Northern Ireland's position within the Union having been secured, it is rather ironic the constitutional approach of Alex Salmond appears to pose a greater threat to the union than the violence of the IRA."

Mr Elliott also accused the SNP of planning to play on a "19th-century romantic-style notion of nationalism" in an opinion column in the Belfast Telegraph newspaper.

A senior SNP source said: "We need serious discussion of the issues not comparisons to the IRA".