JEREMY Corbyn has always believed in the maintenance of the United Kingdom but does not describe himself as a Unionist because it has "divisive" connotations in Scotland, the Labour leader’s office has insisted.

Just before he became his party’s leader Mr Corbyn famously declared he was “a socialist not a Unionist” and revealed that during the entire Scottish independence campaign he had not visited Scotland once to support the No campaign.

Earlier this week, Mhairi Black, the SNP MP, claimed that the Labour leader had once told her that he had supported Scottish independence, a claim strenuously denied by the party, which branded it “complete nonsense”.

But asked if Mr Corbyn had always opposed Scottish independence or if he had at some point changed his mind on the issue, his spokesman replied: “He has been clear all along that he does not favour the break-up of the UK and supports the maintenance of the UK.”

He went on: “This SNP MP is the only one who has suggested otherwise.”

When it was pointed out how Mr Corbyn did not describe himself as a Unionist, the spokesman said: “As we all know the word Unionist in Scotland has certain connotations and meanings, which are divisive in Scotland and the issue of supporting the continuation of the UK and Unionism are not exactly the same thing.”

Asked if it was therefore fair to say the Labour leader had always been against Scottish independence, the spokesman added: “He’s always been in favour of the maintenance of the UK.”

Later, Ian Blackford, the SNP leader at Westminster, was asked if he believed Mr Corbyn was a “secret supporter of independence,” and replied that he did not know the Labour leader’s personal position on the constitutional question. But he noted: “The Labour Party have a long tradition of being hostile to independence."

Asked if he believed Ms Black had been telling the truth when she made her claim, the Highland MP replied: “I have no reason to doubt that Mhairi Black tells the truth.”

Asked about Mr Corbyn not describing himself as a Unionist because it was a divisive term, Mr Blackford said: “I would be very careful about defining things in such a manner. I would never seek to characterise opponents by use of language that might be considered perjorative.

“I believe in Scottish independence, I’m not going to criticise the right of other people to defend what they see as the Union. I think they are wrong but to start to say there are problems with the use of the word Unionist, no, I wouldn’t share that[view],” he added.