MPS have been urged to ramp up efforts to make Boris Johnson accountable to Parliament as Westminster enters its second week of being shut down.

SNP Westminster leader Ian Blackford said the Prime Minister should be brought “back to reality and to Parliament” to answer questions over Brexit plans and the consequences of No Deal.

He also warned Johnson against attempting to ignore legislation passed by MPs to block a No-Deal Brexit, which means the Prime Minister until October 19 to pass a deal – or he will be forced to seek a three-month extension to Article 50.

Johnson will travel to Luxembourg tomorrow for his first meeting with European Commission president Jean-Claude Juncker and EU chief negotiator Michel Barnier, since taking office in July.

On Friday he said he was “cautiously optimistic” of getting a Brexit deal. However Blackford said Johnson must not be allowed to continue with his “business as usual” attitude, while MPs were unable to hold the government to account over issues such as the Operation Yellowhammer documents. The plans, which the Government was forced to publish last week, warn of food shortages, reduced medicine supplies, and low-income families being disproportionately hit by a No-Deal Brexit.

The document stated it represented a “reasonable worst case scenario”, but this was disputed by Nicola Sturgeon who said the report the Scottish Government received had been entitled “base scenario”.

Blackford said: “As Parliament enters its second week of being shut down, I urge MPs from all parties to ramp up efforts and work together in bringing Boris Johnson back down to reality and back to Parliament.

“It is a stain on our democratic institutions that the UK Government can operate in a clandestine way, with rogue ministers publishing conflicting and misleading government documents over the devastating impact of a No-Deal exit. As Boris Johnson continues his meetings with EU leaders he must be reminded of the reality that Parliament has voted by a strong majority to take No Deal off the table once and for all – which the government’s very own Yellowhammer documents reveal will lead to food shortages, reduced medicine supplies, and low income families being disproportionately hit.”

In the meantime SNP MSPs are involved in efforts to hold the UK Government to account while Parliament is in shutdown, the Sunday National can reveal. A series of requests have been sent asking UK ministers to appear before Holyrood committees to answer questions on issues such as Brexit and Yellowhammer.

An SNP source said: “Boris Johnson might think he can avoid scrutiny at Westminster but there’s more than one parliament in the UK. Holyrood is ready to step into the gap and hold the UK Government to account.

“With Westminster shut down, ministers have cleared their diaries and frankly have no excuse not to answer questions in the Scottish Parliament. If they refuse to appear at Holyrood it will just show the contempt with which they hold Scottish democracy – and not for the first time.”

A legal showdown will also take place over Brexit this week, with a hearing beginning at the UK Supreme Court on Tuesday over Boris Johnson’s decision to prorogue Parliament. Last week Scotland’s highest civil court concluded it was “unlawful”, with a damning judgement which implies he mislead the Queen, Parliament and public to “prevent or impede” MPs ability to scrutinise his Brexit plans. A panel of 11 judges will have to decide if they agree with that decision, or another ruling by English judges which concluded it was a political matter that should not be reviewed by the courts.

Dr Nick McKerrell, lecturer in constitutional law at Glasgow Caledonian University, said it was difficult to know which way the judgement would go.

But he said: “The arguments of the Scottish courts were pretty convincing. Given how seismic a shock that was, it wouldn’t be as big a surprise if the Supreme Court sided with that.

“Having said that, there was another judgement which reached the opposite conclusion, so they could side with that.”

Meanwhile Scottish LibDem leader Willie Rennie has denied reports his party is in talks with the Conservatives in preparation for a snap General Election to ensure the SNP does not have a “clean sweep” of Westminster seats.

He insisted there was “no pact” between his party and the Conservatives. Referencing the LibDem coalition Government with David Cameron after the 2010 election, Nicola Sturgeon tweeted: “Leopards – and it seems Liberals – don’t change their spots. According to this they’re in election talks with the Tories?! Remember this the next time you hear the Scottish LibDems claim that they are anti-Tory.”

Rennie replied: “Wrong – no pact between us and Conservatives. We are opposed to Brexit and Boris Johnson and won’t be doing anything to support them.”