Sir Ivan Rogers resigned from the civil service

LONDON - Sir Ivan Rogers has resigned from the civil service, four days after quitting his role as the UK's ambassador to the European Union, the BBC reported.

It means he won't take up any new government role on his return from Brussels.

Rogers, who was appointed the UK Permanent Representative to the European Union by David Cameron in 2013, became a target for the right-wing press and pro-Leave Tory MPs for claiming a UK-EU free trade deal could take 10 years to negotiate and put into effect.

In his resignation letter published earlier this week, Rogers appeared to suggest that his growing frustration with the government's approach to Brexit negotiation played at least some part in his decision to leave the position before exit talks get underway at the end of March.

He encouraged fellow civil servants to "speak truth to those in power" by challenging "ill-founded arguments" and "muddled thinking," in what appeared to be a thinly-veiled swipe at Theresa May and the Brexit ministers.

Former Russian ambassador Tim Barrow was appointed as Britain's new ambassador to the EU on Wednesday.