Theresa May has refused to confirm if the Scottish secretary discussed their party's deal with the DUP which handed an additional £1bn to Northern Ireland.

The Conservative leader and David Mundell's relationship came under scrutiny from the SNP's new Westminster leader, Ian Blackford, at Prime Minister's Questions on Wednesday.

Mundell had previously said he would stand against any "back door funding to Northern Ireland" which would not then qualify for Barnett formula funding to Scotland.

Scotland receives Whitehall funds as a proportion of spending in England. The extra paid to Northern Ireland under the Tory-DUP deal, therefore, does not trigger more money for Scotland.

May did not directly answer Blackford's first question on the subject.

After his second question, the Prime Minister said: "I can assure (Mr Blackford) that I regularly receive representations from the Secretary of State for Scotland about matters relating to Scotland, including regular representations which point out that if the Scottish nationalists actually have the interests of Scotland at heart they will want to remain part of the United Kingdom."

Blackford said May's failure to give a straight answer "speaks volumes and has only succeeded in piling more pressure on the Scottish secretary, whose position now looks less secure with every day that passes".

The deal between the two parties will see the DUP's 10 MPs vote with the Conservatives on budgets and any confidence motions put forward in the House of Commons.