There is a "real possibility" that the Beijing Olympic will be targeted by terrorists or that anti-China groups could attack athletes, Interpol's secretary general said.

"An attempted act of terrorism is a real possibility and a real concern that all Olympic host countries have shared in recent years," Ronald Noble told the opening of the International Conference on Security Cooperation in Beijing.

"Recent Tibet-related protests have introduced significant additional complications to the normal security considerations for a major international event like these Olympics."

The international leg of the Olympic torch relay has been dogged by pro-Tibet and anti-China protests, following unrest in Tibet last month in which China says about 20 people died.

"In light of recent events, all countries whose athletes will participate and whose citizens will attend the Beijing Olympics must be prepared for the possibility that the groups and individuals responsible for the violence during the global torch relay could carry out their protests at the actual Games," Noble said.

"These activities could range from disruptive behaviour, like blocking major transportation routes or infrastructure or interfering with competitions, to more violent acts like assaulting Olympic officials or athletes or destroying property," he added.

"Worse yet, we must be prepared for the possibility that al Qaeda or some other terrorist group will attempt to launch a deadly terrorist attack at these Olympics."