Anti-globalisation protestors have forced the World Economic Forum (WEF) founder, Klaus Schwab, to delay a planned speech in Zurich in which he stressed the importance of social responsibility.
Up to 100 demonstrators blocked the entrance to the main conference hall at Zurich's Federal Institute of Technology and prevented Schwab from reaching the podium.
Rolf Probala, spokesman for the Institute, said the hall was already packed with members of the public when the protesters arrived to block the entrance.
"After about half an hour," he said, "we decided that for security reasons it would not be possible for Klaus Schwab to give his planned speech in the main hall."
The venue was hastily moved to a different location inside the Institute, with a far smaller seating capacity.
Schwab expressed regret that his speech, in which he called for a "shift away from confrontation to cooperation", could only be heard by a vastly reduced audience.
Zurich cantonal police had been drafted in to assist with the security operation, but there were no reports of violent confrontation between organisers and protesters.
Controversy has dogged the WEF since its summit in Davos in January, when anti-globalisation protesters were prevented from reaching the forum venue by police, who blocked rail and road routes into the Swiss alpine resort.
Before the appearance of the WEF founder in Zurich, anti-globalisation pressure groups had called on their supporters via the Internet and through the dispersal of leaflets to attend the meeting and force the cancellation of Schwab's keynote address.
swissinfo with agencies