David Mundell told "do your job" as UK promises to intensify talks

David Lidington, the minister put in charge of talks with the SNP administration in this week's reshuffle, told MPs the government was hopeful of making a breakthrough when the EU Withdrawal Bill reaches the House of Lords.

It comes as Scottish Secretary David Mundell faces criticism for failing to keep to a commitment to amend Clause 11 of the bill before the final stage of scrutiny in the House of Commons.

The government was forced to admit on Tuesday that it had run out of time do make the changes demanded by opposition parties and its own Scottish MPs. Fears have been raised on all sides that the legislation will lead to a post-Brexit 'power grab' over 111 responsibilities in devolved areas that are currently held in Brussels.

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The Scottish and Welsh Governments have said they will refuse to give legislative consent to the Withdrawal Bill as currently drafted, risking a constitutional crisis. On Wednesday Scottish ministers wrote to the Holyrood presiding officer Ken Macintosh informing him that a 'continuity bill', directly challenging Westminster's authority over the disputed powers, would be introduced in the Scottish Parliament in February and asking for it to be passed on an accelerated timetable.

At Prime Minister's Questions, SNP Westminster leader Ian Blackford told Theresa May she had "one last chance" to produce amendments before the final Commons debate next week, warning: "The Tories always promise Scotland everything and deliver nothing."

In a stark message to the Scottish Secretary, Mr Blackford later said: "David, do your job. You're there to be the Secretary of State for Scotland. Demonstrate to the country that you can do that."

He also said that "it would be appropriate for David and for the government to apologise, because the people in Scotland, Wales and Northern Ireland have been misled."

Mr Mundell is understood to have approached Scottish MPs privately to apologise for the delay.

The SNP's Westminster leader, who said the government could still rush forward amendments before next week's debate, said there was "still time to not only respect the institutions of the devolved administrations, but to respect their own backbenchers who were promised this."

Mr Blackford suggested Scottish MPs on the government benches could push forward their own amendments next week, adding: "I think the people of Scotland will be looking at [the Scottish Tory MPs], because they have got to demonstrate that they are standing up for the interests of the people of Scotland, and they're not going to allow this power grab to take place to the extent that is currently happening."

Mr Lidington, a former Europe Minister whose appointment as Cabinet Office minister has been welcomed by SNP insiders, spoke to the Deputy First Minister John Swinney on Tuesday and is expected to travel to Scotland within days to restart the dialogue between London and Edinburgh.

A plenary meeting of the Joint Ministerial Committee, involving Theresa May and the heads of the devolved administrations, is expected early next month.

Facing questions in the Commons earlier on Wednesday, Mr Lidington was challenged by Paul Masterton, the Conservative MP for East Renfrewshire, who had voiced frustration that amendments were only being made in the Lords.

"The minister will be aware that personal assurances we given to me and colleagues that the Government would bring forward amendments to clause 11 of the repeal Bill, but they have failed to do so," Mr Masterton said, calling on the minister to "assure me that the government remain committed to working with the devolved administrations to find a form of words that will be agreed and will allow a legislative consent motion to be passed."

Mr Lidington replied: "When I spoke to the Deputy First Minister of Scotland last night, I said that we were disappointed that we had not been able to reach agreement with the devolved administrations on an acceptable form of words for such an amendment but that I was committed to intensifying our discussions with the devolved administrations to seek to reach an agreed form of words in time for proceedings in the House of Lords."