British Prime Minister Theresa May has declined to say whether she would vote for Brexit if there was another referendum.

May backed staying in the European Union in the June 2016 Brexit referendum but took a low-key role in the campaign. She won the top job after David Cameron, who had also campaigned to remain, resigned in the chaos following the shock result of the vote.

Asked if she had changed her mind since then, she said she did not answer hypothetical questions and said her job was now to deliver what the people had voted for.

"I voted remain for good reasons at the time, but circumstances move on and I think the important thing now is that I think we should all be focused on delivering Brexit and delivering the best deal," she said on an interview on LBC radio Tuesday.

Pressed on whether she would now vote leave, she said she would look at everything and come to a judgment, but stressed that there would not be another referendum.