Conspiracy theories driven by social media are driving Labour's collapse in Scotland, a leading Labour MP claimed today.

Shadow foreign secretary Douglas Alexander told a conference in London that Scottish voters were suffering from an irrational grief amplified by social media.

"Forty-five per cent of Scots voted 'Yes' and 55% voted 'No'. Amongst the 45% who voted 'Yes' there's a great sense of grief and sometimes grief presents itself as anger," he told the LabourList conference.

"Some of them blame the BBC and some of them blame the Labour party."

He spoke about an "intelligent woman" he met in a supermarket who claimed that the referendum result was a conspiracy.

"An intelligent woman, a social worker, came up and told me 'I'm never going to vote Labour again.'"

"'I'm very disappointed in the referendum. I don't believe the referendum result.' Do you think it was a conspiracy? 'Yes I do. Everybody I know voted 'Yes''".

He said the rise of social media was making it difficult to get through to these angry 'Yes' voters.

"We're used to a politics where we share facts but diverge on opinions," he said.

"We are confronting increasingly, with voters' eyes on social media, a politics which is an echo chamber of people's own opinions.

"How do we engage with a very rapidly changing media landscape in which facts are not common and people have their own facts?"

Alexander currently faces losing his seat to the SNP according to constituency polling by Lord Ashcroft.

He admitted that "the numbers are not good," but insisted that the stark choice between a Labour and Conservative government would concentrate voters' minds.

Asked whether he was among those Scottish Labour MPs who had called on Miliband to take a clearer stance on a possible post-election deal with the SNP he replied that "private conversations would remain private."