The SNP MP Mhairi Black made headlines this week when she claimed Mr Corbyn had “betrayed” Scotland over the issue of its constitutional future, and had voiced sympathy for independence in private conversation.
Questioned about the comments, the Labour source said Ms Black’s claims were “fanciful”, and insisted Mr Corbyn “has been clear all along that he doesn’t favour the breakup of the UK”.
But the spokesman added: “As we all know, who deal with these issues, the word Unionist in Scotland has a set of other connotations and meanings, which are divisive in Scotland, and I think the issue of supporting the continuation of the UK and Unionism are not exactly the same thing.”
In 2015, the Labour leader said in a newspaper interview that he was “not a Unionist, I’m a socialist”. He has been criticised by senior Scottish Labour figures for his failure to campaign in the 2014 Scottish independence referendum, and for previous comments suggesting he is open to a second vote on the issue.
The comments were swiftly criticised from an surprising source - the leader of the SNP at Westminster.
“I would be very careful about defining things in such a manner, and I would never seek to characterise opponents by the use of language that might be considered pejorative,” Ian Blackford said.
“[The SNP] believe in Scottish independence. I’m not going to criticise the right of other people to defend the Union. I think they’re wrong, but to start to say that there are problems with the use of the word Unionist - no, I wouldn’t agree with that.”