Conservative leadership front runner Boris Johnson poses a "real and present danger" to the union, Scottish Labour leader Richard Leonard has insisted.

He hit out at the former foreign secretary, who recently vowed to fight to keep Scotland in the United Kingdom "with every fibre in my being, with every breath in my body".

But Mr Leonard accused the former London mayor of having abandoned the traditional policies of the Conservative and Unionist Party and instead focusing on "English nationalism".

With polls showing a possible increase in support for Scottish independence if Mr Johnson becomes the next PM, the Labour MSP said his party would not campaign alongside the Tories if there were another referendum.

Mr Leonard told PA: "My concern is that Boris Johnson represents a new strain of politics, which is an abandonment of conservatism and unionism and the adoption of an English nationalism.

"For that reason he poses a real and present danger to the United Kingdom and the integrity of the United Kingdom, which is why we have been campaigning in Glasgow this morning, getting across the message that if you want to stay part of the UK don't look to the Conservatives.

"You're going to have to look to Labour, because we are the only party which is defending the integrity of the United Kingdom."

He told how he had been "opposed to the Better Together campaign approach the Labour Party took" in the run up to the 2014 vote - when Scots rejected independence and opted to stay in the UK by 55% to 45%.

Mr Leonard said: "I thought there should always have been then an autonomous, distinctive, Labour case made for voting 'No' in that referendum, but with a view to reform and change.

"Nothing in my mind has changed about that, I think it is clear to me that if there is a future independence referendum - and I'm not persuaded there is a case for it, that even with the election of Boris Johnson as prime minister there is a deepened appetite for it - were there to be a future referendum campaign, we would adopt a distinctive Labour approach to that which is based upon reform of the United Kingdom and remaining in the United Kingdom."

Speaking at an event in Motherwell to promote Labour's policy for a "green industrial revolution", Leonard also stated his belief that more powers should be devolved to Holyrood and insisted that the House of Lords should be abolished.

He revealed that the party set up a working group to explore "options for change that delivers more devolution".

On the House of Lords he added: "I think there is a compelling case in the modernisation of the UK for the abolition of House of Lords and potentially its replacement with a senate which would be made up of representatives of the constituent parts of the UK."