London mayor Sadiq Khan has called for a second EU referendum, criticising the government's handling of Brexit negotiations with the EU.
Writing in the Observer, the Labour politician said that with the UK due to leave the EU in six months, it now faced either a "bad deal" or "no deal".
The debate had also become "more about Boris Johnson's political ambitions" than what was good for the UK, he said.
PM Theresa May has said a second vote would be a "betrayal of our democracy".
The former Tooting MP said that although he campaigned to remain in the EU, he had accepted "the will of the British people was to leave the EU".
He said he had never expected to back calls for a second referendum, but had become "increasingly alarmed as the chaotic approach to the negotiations had become mired in confusion and deadlock".
With time running out for the British government to negotiate a final deal with the EU before March 2019, Mr Khan said the UK was left with two "incredibly risky" possibilities.
BDST: 1347 HRS, SEPT 16, 2018