The UK’s top diplomat to the EU has resigned.

The abrupt departure of Sir Ivan Rogers comes just a few months before Prime Minister Theresa May is expected to start formal Brexit negotiations.

Rogers, appointed by former Prime Minister David Cameron as the UK’s permanent representative to the EU in November 2013.

He is one of the UK’s most experienced diplomats on EU affairs.

He told staff on Tuesday afternoon that he would be stepping down early from his post.

He has not yet explained the reasons for the decision.

Theresa May has said she will trigger formal Brexit talks with the rest of the EU by the end of March.

There has been no comment so far from Downing Street and the UK Foreign Office.





In tweets

Shock as Sir Ivan Rogers, UK ambassador to the EU, resigns https://t.co/nmuCNTHKCg pic.twitter.com/Hvr22YP5kF— POLITICO Europe (@POLITICOEurope) January 3, 2017






Ivan Rogers resigns as U.K.’s ambassador to EU https://t.co/MjnQPV7VPB— WSJ Europe (@WSJeurope) January 3, 2017






Ivan Rogers' resignation makes a good deal on Brexit less likely. One of the v few people at top of Brit govt who understand EU. CER_London— Charles Grant (CER_Grant) January 3, 2017






In any negotiation you need to understand the people on the other side of the table. Ivan Rogers knew the EU better than most in London.— Chris Morris (@BBCChrisMorris) January 3, 2017