THE resignation of David Davis as Brexit Secretary has confirmed the UK government’s descent into “utter chaos”, Nicola Sturgeon has said.

The First Minister said Theresa May’s administration was now simply a “shambles”.

Ms Sturgeon tweeted her verdict as SNP MPs were being asked to attend a Downing Street briefing on the Prime Minister’s Chequers deal by her of chief of staff Gavin Barwell.

Mr Barwell has offered a briefing on Mrs May’s Brexit proposals to all opposition MPs, in a sign Number 10 knows it cannot rely on the support of Tory MPs alone to make them work.

READ MORE: David Davis quits as Brexit Secretary in major blow to Theresa May

Leading Brexiter Tory MP Jacob Rees-Mogg said it showed Ms May would need “social votes” to get her scheme through parliament.

After quitting on Sunday night, Mr Davis said this morning that he could not have sold Mrs May’s Brexit proposals in Brussels as he did not believe in them.

They were giving away “too much, too easily”, Mr Davis said on BBC Radio 4.

Ms Sturgeon wrote: “The Chequers unity didn’t last long. This UK government is in utter chaos and ebbing authority by the day. What a shambles.”

Carwyn Jones, the Labour First Minister of Wales, added: “The resignation of David Davis shows that the UK Government is in complete disarray over Brexit and action urgently needs to be taken to resolve this chaos - businesses need certainty and the country needs leadership and direction.”

Scottish Labour leader Richard Leonard called for a general election.

He said: “Theresa May has no authority left. The Prime Minister is in office but not in power. This is not sustainable.

“In the interests of the great majority of people in Scotland and across the United Kingdom, we must have a General Election.”

Shadow Chancellor John McDonnell tweeted: "With such instability in government it's impossible to see how EU leaders could take Theresa May seriously in the next round of negotiations. It's time for her and her party to put country before party and go."