David Cameron is to attend a behind-closed-doors meeting of global business leaders, politicians and academics that critics say is too secretive.
Downing Street said the prime minister had been invited to the Bilderberg meeting in Hertfordshire in his role as head of the government hosting it.
Other politicians listed as attending are Ken Clarke, George Osborne, Lord Mandelson, Ed Balls and Lady Williams.
Protesters heckled those arriving at the four-day event on Thursday.
The annual Bilderberg meetings of the world’s political and financial elite are pitched as a forum for “informal, off-the-record discussions about megatrends and the major issues facing the world”.
The Bilderberg Group say the private nature of the conferences allow people to “listen, reflect and gather insights” without being bound by “pre-agreed positions”.
But critics say the numbers of people attending – around 140 are invited from Europe and the US – mean it should be more accountable.
Downing Street confirmed Mr Cameron’s attendance on Friday, saying he would “participate in a discussion around domestic and global economic issues”.
“He feels it is an opportunity to discuss economic issues with senior ministers, businesspeople and academics,” a spokesman said.
The Bilderberg group says that topics to be discussed at its 2013 meeting include economic growth, cyber warfare, medical research trends, Middle East developments and EU politics.
Other attendees include business leaders like Google boss Eric Schmidt, prime minister of the Netherlands Mark Rutte, former US commander in Afghanistan and former CIA director General Petraeus and former Barclays chairman Marcus Agius.
Downing Street indicated it would not be providing a summary of Mr Cameron’s discussions to the press but denied it was a departure from the prime minister’s pledge to lead the most transparent government in the world.
“The prime minister regularly has meetings with key ministers from other countries and with business people and others as part of his job,” the spokesman said.
“We have advanced the fact that he is doing this today. It is not as though he has gone to do this without telling anyone about it.”
Labour MP Michael Meacher, who was among protesters outside the Grove Hotel on Thursday said: “These are people who are all in the most dominant positions in the governance of Western capitalism.
“They only meet in order to concert their plans about the future of capitalism over the immediate future period – the next year or two.
“My objection is that it’s being done in utter secrecy with the police keeping everyone else out.”