Britain's ambassador to the EU has resigned 3 months before Brexit talks begin

LONDON - The British ambassador to the European Union has just unexpectedly resigned three months before Theresa May intends to trigger Article 50 and initiate exit talks. 

Sir Ivan Rogers, who worked closely with former prime ministers David Cameron and Tony Blair, told staff on Tuesday afternoon that he'll be leaving his post much earlier than expected, the Financial Times reports. 

Rogers is one of Britain's most experienced negotiators and was set to play a key role in Brexit negotiations with EU leaders, which are set to get underway in three months time. Rogers did not give a reason for his shock resignation, according to sources who have seen the note he sent to colleagues. 

This is a developing story...