A furious row erupted yesterday after a Tory peer used a No campaign event to warn of a "poison at the heart of Scottish politics".

At the Better Together London group launch, Lord Strathclyde called for the poison to be "eradicated once and for all" at next year's independence referendum.

The SNP angrily accused the former leader of the House of Lords of abusive language and a denigration of nationalism and demanded an apology from Alistair Darling, the leader of the No campaign.

The peer said he was stunned at the response and denied his remarks were directed at nationalism. He said: "Something has been lost in translation. I thought it was quite obvious [what I was saying] and I stand by my remarks.

"The poison is of course the uncertainty. What I want is a referendum, which I believe is SNP policy. They are asking me to apologise for their policy, which I will not do."

Lord Strathclyde told a hall of about 200 people "a poison has been introduced right at the heart of Scotland and of Scottish politics and it is that poison that needs to be resolved in referendum".

The SNP's Westminster leader Angus Robertson accused him of using abusive language, which he said had no place in the referendum debate.

l Independence would create a "renewed partnership" between Scotland and the rest of the UK, Nicola Sturgeon has claimed.

In a speech at Edinburgh University, the Deputy First Minister said: "We can take back the powers we need to meet our economic and social aspirations and play our full part, together with our closest allies, neighbours and friends, in a renewed, stronger, positive partnership of these isles."