LONDON, England -- Several hundred protesters have staged a sit-down demonstration outside the venue of a conference where former U.S. Secretary of State Henry Kissinger is due to speak.

The protesters gathered at London's Royal Albert Hall as thousands of business leaders arrived for the annual Institute of Directors (IoD) convention on Wednesday.

Anti-globalisation demonstrators were joined by a group campaigning against Kissinger.

They banged drums and chanted "war criminal" and "this is what democracy looks like."

A huge puppet depicting Kissinger was erected on the pavement outside the venue by several people calling themselves the Get Kissinger Group.

The group plans to hold a mock trial accusing the 78-year-old of being a war criminal because of his involvement in events in Vietnam, Laos and Cambodia.

Kissinger's appearance in London has caused some controversy among civil rights groups and some left-wing MPs.

And a Spanish judge has asked U.S. authorities for permission to question Kissinger about "Operation Condor," a concerted plot by former military dictatorships in Brazil, Argentina, Chile, Paraguay and Uruguay to persecute and eliminate their opponents during the 1970s and 1980s.

On Tuesday, Britain refused Judge Baltasar Garzon's request for permission to question Kissinger while he is in London.

Garzon has said he only wants to question Kissinger as a witness, not a suspect, as part of his investigations into "Operation Condor."

On Monday, Labour MP Jeremy Corbyn tabled a House of Commons motion expressing the hope "that his presence in Britain will be used as an opportunity for the police to interview him regarding allegations of human rights abuses during Operation Condor in Latin America in the 1970s".

"We believe that Kissinger's involvement in the coup in Chile in 1973 and in support of the military regimes in the region places him in a unique position to give insight into the perpetrators of these abuses of human rights," the motion added.

Also on Monday, British human rights campaigner Peter Tatchell failed in his attempt to have Kissinger arrested in Britain for alleged war crimes under the Geneva Conventions Act.

Tatchell alleged that Kissinger's direction of the Vietnam War of the 1960s and 1970s amounted to a breach of British laws requiring people of all nationalities to observe the Geneva Conventions on the conduct of war.

Kissinger was former U.S. President Richard Nixon's National Security Advisor from 1969-1973 and secretary of state between 1973-1977.

George Cox, director general of the IoD apologised to the 2,500 delegates for inconvenience caused by the strict security at the Royal Albert Hall because of the protests.

He accused the protesters of stifling debate and said they themselves were part of globalisation.

He said: "They are an international movement, they communicate with satellite phones, they wear their Nike gear, travel by global airlines and plan their demonstrations using perhaps the greatest of all drivers of globalisation -- the Internet.

"To call for an end to globalisation is to call for an end to the weather -- it is unstoppable.

"Globalisation isn't the best hope for the poor of the world, it is the only hope."