Jeremy Corbyn has added to Scottish Labour’s woes by refusing to say that he would block another independence referendum.

The Labour leader said that he would allow a vote "if the Scottish Parliament and the Scottish people want it".

On Monday Mr Corbyn threw Labour north of the Border into turmoil after he said that he would “open discussions” on another poll with the SNP if he won the keys to No 10 next month.

But the Scottish Conservatives said that his latest comments had exposed Scottish Labour’s claim to be opposed to a second referendum “as a complete sham”.

Scottish Conservative MSP Murdo Fraser said that his remarks showed that "Mr Corbyn would sell us all out in Scotland in a heartbeat”.

The row erupted just hours before a car-crash radio interview in which Mr Corbyn was unable to say how much one of his party's flagship election pledges would cost.

Scottish Labour insists that it remains utterly opposed to a second referendum.

Last week Scottish Labour leader Kezia Dugdale offered Scots a "cast-iron guarantee'' that Labour would oppose a another vote.

But Theresa May has said that the SNP would “pull the strings” in any minority Labour government, with a referendum the price of their support.

On a campaign visit in London Mr Corbyn suggested that he would allow a second referendum "if the Scottish Parliament and the Scottish people want it" because that was the "whole point" of devolution.

He also said that any vote should take place after the UK leaves the European Union (EU) in March 2019.

Mr Corbyn was asked if he would block a referendum, late next year or early the year after, if it was backed by MSPs.

He replied: "I would urge them to think again and I would appeal to the Scottish people to think again on this.

"Let's deal with the Brexit negotiations first," he added.

Pressed again if he would block a referendum before Brexit is complete, Mr Corbyn replied: "We would discuss it with them and urge them very strongly to put it back until after the Brexit talks have been concluded and I think there would be a reasonable agreement around that because, after all, in Scotland the issues are actually poverty, actually on investment, actually on the housing needs of the people of Scotland."

On the principle of the issue, Mr Corbyn added: "What I've said is that if the Scottish Parliament and the Scottish people want a referendum, they have the right to do that, that was the whole point of the devolution agreement of the 1990s.

"I think the referendum should take place, if there is to be one, after the Brexit negotiations are concluded because this is the most important thing."

Scottish Liberal Democrat MSP Alex Cole-Hamilton said: "Scottish Labour must be pulling their hair out as last time I checked this wasn't their policy."

MSPs have already backed a motion calling for Holyrood to have the powers to hold another independence referendum.

Ms Sturgeon has argued that the UK that Scots voted to remain a part of in 2014 no longer exists in the wake of last year's Brexit vote.

Mrs May has rejected calls for another vote saying that "now is not the time".

Mr Corbyn also came under fire for not knowing the cost of one of his party's main election pledges after he tried to look for the answer on his iPad during a live radio interview.

The Labour leader also flicked through his own manifesto in a bid to try to find the number during the chat with BBC Radio 4's Woman's Hour, according to presenter Emma Barnett.

She later told him that Labour had estimated that the cost would be £2.7bn a year.

Senior Labour figures have consistently struggled with figures related to their own policies during this election.

In a car crash radio with LBC shadow Home Secretary Diane Abbott said that her party's plans to recruit 10,000 policemen and women over a four-year period would cost about £300,000.

She later claimed the cost would be about £80 million.

Labour has unveiled plans for to roll out free childcare to all two-to-four-year-olds in England.

Despite the gaffe, Mr Corbyn later added to speculation he intends to stay on as Labour leader if he loses the General Election.

In an interview with the website Mumsnet he refused to give a ‘yes or no’ answer when asked whether he would stand down if Labour is defeated.

Later Mumsnet users expressed their fury after Mr Corbyn left just 25 minutes into the chat, saying that he had to run for a train.

During the interview he also said that he was “looking forward” to meeting Donald Trump, but in an aside at Mrs May he added he would not hold the hand of the controversial American President.

Today Mr Corbyn will try to turn the focus back on public services, telling voters in England that “the futures of our NHS and schools are at stake in this election".