A giant clock started ticking yesterday in Tian'anmen Square, at the very heart of the Chinese capital, counting down the days, hours and minutes to the Beijing 2008 Olympic Games.

With four years to go until the 29th Olympiad in Beijing, the launch of the clock shows the official countdown for the games is now under way.

The ceremony to present the timepiece by the Beijing Organizing Committee for the Games of the XXIX Olympiad (BOCOG) was simple yet full of significance.

At 6 pm, the countdown clock was jointly started by Liu Jingmin, executive vice-president of the BOCOG, Wang Yifu, Athens Olympic Games gold medalist, a Beijing resident Li Changxin, a middle school student Wang Yu and Stephen Urquhart, President of OMEGA.

At the same time, a countdown clock for the Beijing Games was also placed in Qingdao, a coastal city in East China's Shandong Province, the host city for the sailing events of the 2008 Games.