The SNP's protest at Prime Minister's Questions "most certainly isn't" a one-off, the party's Westminster leader has warned.

Ian Blackford said it would "not be business as usual" as he signalled the SNP's "real determination" to hold the Government to account over its Brexit legislation.

Scottish Secretary David Mundell's position is "untenable" he added, having "failed to defend Scotland's interests" through the EU (Withdrawal) Bill.

Mr Blackford was ordered out of the Commons chamber following a row with Speaker John Bercow during PMQs last week.

His SNP colleagues then walked out as part of their protest over what they claim is a "power grab" over Brexit.

Mr Blackford told the Press Association: "Is what we did last week, is that a one-off and is that the end of it?

"It most certainly isn't and what we do want to signal to the Government in London (is) that this will not be business as usual, our relationship with the Government, which will remain courteous, will be very different and we will seek to hold the Government to account as and when we can.

"Now of course we're not going to signal to the Government exactly how and when we will do that, we are looking at a number of things that we can do.

"This will be procedural, this will be what we can do around legislation, but we'll do it on the basis that we're discharging our duty to stand up for Scotland, but it'll be done in a way which is dignified, which does show respect, we will not show discourtesy.

"But it will be absolutely crystal clear that there's a real determination that we have, and if I may say so as well that our colleagues that we work closely with in the Scottish Government have, that Westminster has to understand that we cannot accept what is taking place."

The UK Government has previously said the Bill delivers on its pledge to give "significant further powers" to the Scottish Parliament, and it would seek consent unless there are "not normal circumstances applying" - describing Brexit as such an exception.

The Scottish Parliament has not granted a legislative consent motion for the key Brexit legislation.

Mr Blackford earlier said the Government has to bring forward emergency legislation which respects devolution, the Scottish Parliament and the Scottish people.

Asked if the ball was in their court, he said: "It is, one I think the Government has got to bring forward legislation, two I think they have got to enter into talks through the joint ministerial committee with the Scottish Government but it has to be on that basis that they understand that they've crossed the line and this is not acceptable.

"I think on the basis of where we are at the moment, I do think that David Mundell's position is untenable."

Mr Blackford claimed Brexit Secretary David Davis was "more appreciative and understanding of the position that we're taking", adding: "I think what the Government in London needs to have is someone that's a Secretary of State that understands the devolution settlement."