Theresa May has said she will quit as Conservative leader on 7 June, paving the way for a contest to decide a new UK prime minister, BBC reports.
In an emotional statement in Downing Street Mrs May said she had "done my best" to honour the 2016 EU referendum result.
It would remain a matter of "deep regret" that she had been unable to deliver Brexit, she added.
But a new PM was "...