Downing St disclosed that the Prime Minister would attend the controversial gathering of heads of governments, former ministers, and chief executives of the world’s most powerful global corporations.

However, the discussions, on Friday, were being held on a strictly confidential basis and Number 10 said no details of the talks would be made public.

Michael Meacher, the Labour MP and former minister, will demand that Mr Cameron makes a statement to the Commons next week giving details of the meeting.

Downing Street insisted that despite the secretive meeting, the Prime Minister remained “determined to lead the most transparent government” in history, a promise he made in 2010.

More than 130 delegates from 21 countries are expected to attend the three-day event at a luxury hotel near Watford. Mr Cameron has been invited as head of the host nation’s government, a Number 10 spokesman said.