British Prime Minister Theresa May forced her most senior minister, Damian Green, to resign on Thursday after an internal investigation found that he had made misleading comments about pornography found on computers in his parliamentary office.

The resignation of one of May's most trusted allies who had helped pacify her deeply divided party, is a blow for May as she navigates the final year of tortuous Brexit negotiations before Britain's exit from the European Union in March 2019.

Green, who voted to stay in the EU, was appointed as first secretary of state just six months ago in a bid to shore up May's prime ministership in the wake of her disastrous bet on a June snap election, which lost her party its majority in parliament.