Image copyright Reuters Image caption Sir Ivan stepped down from his role as the UK's ambassador to the EU on Tuesday

Sir Ivan Rogers has resigned from the civil service, days after quitting as the UK's ambassador to the EU.

The Foreign and Commonwealth Office (FCO) confirmed he would not continue with any role within the civil service.

Sir Ivan stepped down from his ambassador role on Tuesday, criticising "muddled thinking" within government about Brexit.

The government said he had quit early so a successor could be in place before negotiations start.

An FCO spokesman said Sir Ivan had not sought any further civil service appointment, adding it was "grateful" for his work in Brussels and across his other senior positions in the service.

Sir Tim Barrow, a former UK ambassador to Moscow, has replaced Sir Ivan as Britain's EU ambassador. He was described by No 10 as a "seasoned and tough negotiator".

Who is Sir Ivan Rogers?

Sir Ivan is a veteran civil servant whose previous roles include acting as private secretary to ex-chancellor Ken Clarke, principal private secretary to ex-PM Tony Blair and Mr Cameron's Europe adviser.

Appointed by David Cameron in 2013, he was expected to play a key role in Brexit talks, which are expected to start within months. He had been due to leave his post in October.

Sir Ivan sparked criticism last month when he privately told ministers a UK-EU trade deal could take 10 years.

But Prime Minister Theresa May said she will trigger formal talks between the UK and the EU by the end of March, setting in place a two-year negotiation process.

In a resignation email to staff he cited a lack of "negotiating experience" in Whitehall and warned the government would only achieve the best for the country "if it harnesses the best experience".

Sir Ivan said "it would obviously make no sense for my role to change hands later this year."

Downing Street said it would not directly comment on Sir Ivan's resignation email and criticisms of its handling of Brexit but did say he was "free to express his own opinions".

Image copyright Foreign Office Image caption Sir Tim Barrow is the new UK ambassador to the EU

Sir Ivan's resignation comes after some MPs accused him of "pessimism" over Brexit and being "half-hearted" towards leaving the EU.

Former cabinet minister Iain Duncan Smith said when a civil servant "starts going public", ministers "can no longer trust that individual".

Pro-EU MPs described the loss of Sir Ivan's experience as a blow to the government's negotiating strategy.

Former chancellor George Osborne said he was a "perceptive, pragmatic and patriotic public servant" while the Treasury's former top civil servant, Lord Macpherson - who is now a crossbench peer - said his departure marked a "wilful" and "total destruction" of EU expertise within Whitehall.

But former UKIP leader Nigel Farage welcomed Sir Ivan's resignation, adding: "The Foreign Office needs a complete clear-out."

Sir Ivan's deputy in Brussels, Shan Morgan, announced in November that she would be leaving the post to become the Welsh government's permanent secretary.