Chinese President Hu Jintao lit a cauldron at Beijing's Tiananmen Square with the Olympic torch this morning, marking the official start of the round-the-world relay.

The ceremony kicked off on the square at the heart of Beijing two hours after a specially chartered Air China plane carrying the flame from Greece touched down at about 9 a.m.

Vice President Xi Jinping, member of the Political Bureau Standing Committee of the Central Committee of the Communist Party of China (CPC), addressed the ceremony.

Zhou Yongkang, member of the nine-man Political Bureau Standing Committee, and other CPC and state leaders attended the ceremony.

Also present was International Olympic Committee (IOC) Coordination Commission chairman Hein Verbruggen, who addressed the ceremony on behalf of IOC president Jacques Rogge.

The flame is scheduled to depart from Beijing on Tuesday for the Kazakh city of Almaty, the first stop in its global tour of 135 cities.

The relay will cover 137,000 kilometers in 130 days before the flame finally arrives at the National Stadium in Beijing on Aug 8,2008 for the opening ceremony.