SHANGHAI: The city's public security department yesterday vowed to crack down on all kinds of criminal activities and step up efforts to improve public safety ahead of the 2010 World Expo.

In an online chat with the public, Zhang Xuebing, Shanghai's public security bureau chief, said security preparations for the Expo had entered a crucial stage.

"Security measures in the city will be further strengthened to ensure the 2010 Shanghai Expo goes off peacefully," he said.