Boris Johnson’s Brexit minister has resigned from the cabinet and will depart in the new year.

Lord Frost quit in a letter to the prime minister last week, but won’t officially leave until January.

Sky News’ deputy political editor Sam Coates reports that Lord Frost goes “on good terms”, but he is unhappy with the direction of government – high taxes, net-zero and most recently COVID regulations.

As the “architect” of Brexit, Coates said Lord Frost’s departure is set to be “extremely significant” for Mr Johnson, whose primary aim is to “get Brexit done”.

Labour’s shadow Brexit minister, Jenny Chapman, tweeted: “As if we didn’t already know, Lord Frost resigning shows the government’s in chaos.

“The country needs leadership not a lame duck PM whose MPs and cabinet have lost faith in him.

“Boris Johnson needs to apologise to the public and explain what his plan is for the next few weeks.”

The resignation is yet another blow for Downing Street which has lurched from crisis to crisis in recent weeks, including the Christmas parties scandal.

Sky News understands Lord Frost, 56, is unhappy with the direction the government is taking.

He believes taxes under Boris Johnson are getting too high.

And Lord Frost is also said to opposed to the emphasis placed on the Net Zero strategy to reduce carbon emissions.

But the final straw is said to be the re-introduction of COVID regulations due to the spread of the Omicron variant.

Meanwhile Labour deputy leader, Angela Rayner, said Downing Street was in “total chaos” as the nation faces an “uncertain few weeks”.

She blasted Mr Johnson for not being “up to the job”, tweeting: “We deserve better than this buffoonery.”

Liberal Democrat foreign affairs spokesperson, Layla Moran, criticised Mr Johnson for being “weak” at a time the country is in need of strong leadership.

“This shock resignation is a sign of the chaos and confusion at the heart of this Conservative government,” Ms Moran tweeted.

“The rats are fleeing Boris Johnson’s sinking ship as he lurches from crisis to crisis.”

Referring to the North Shropshire by-election which proved disastrous for the Conservatives, Ms Moran added: “Even the Prime Minister’s once-loyal supporters are now abandoning him, just as lifelong Conservative voters are switching in their droves to the Liberal Democrats.”

It comes amid ongoing wrangling over the Northern Ireland protocol.

Lord Frost has been locked in tense talks with European Commission vice-president Maros Sefcovic as the UK and the EU attempt to close gaps in post-Brexit arrangements.

Northern Ireland’s former first minister Arlene Foster described Lord Frost’s resignation as “enormous”.

She tweeted: “The resignation of Lord Frost from the Cabinet is a big moment for the Government but enormous for those of us who believed he would deliver for NI.”

Reacting to the news, DUP leader Sir Jeffrey Donaldson MP said Lord Frost’s departure is a bad sign for Mr Johnson’s commitment to removing the Irish Sea border.

Sir Jeffrey hit out at the government for being “distracted by internal strife” as he suggested Lord Frost was “frustrated on a number of fronts”.

“We wish David well,” the DUP leader said. “We enjoyed a strong relationship with him and his team but this raises more serious questions for the prime minister and his approach to the NI Protocol.”

And he slammed the Protocol as a “deeply damaging deal for the people we represent”.

Sir Jeffrey warned Mr Johnson must “urgently decide which is more important – the Protocol or the stability of the political institutions.”