FORMER Labour chancellor Alistair Darling will speak at the Scottish Conservative conference in defence of the Union, prompting scathing criticism from the SNP.

The chair of the Better Together campaign will line up with senior Tories at a Better Together fringe event next Saturday. The conference handbook says: "We're delighted to welcome Alistair to our conference."

SNP MSP Annabelle Ewing said many Labour voters would be "appalled at the prospect of Alistair Darling going along to the Tory conference to get his instructions".

Deputy First Minister Nicola Sturgeon, who will appear with Darling at a conference on independence on Tuesday, added: "Alistair Darling will this week try to continue his ridiculous argument that the people of Scotland are best served by economic policies he has described as 'utterly mad'."

Better Together said it was the nature of politics for people to disagree over policy. "Keeping Scotland a part of the UK is so important to him that, despite these differences, he is working the other parties to make sure that we win the referendum."