BEIJING, July 11 (Xinhua) -- The first full dress rehearsal of the opening ceremony of the Beijing Olympic Games was held in secret at the National Stadium on Thursday night, reported China's Central Television (CCTV).

    Tight security was deployed outside the stadium to keep the program of the three-and-a-half hour opening ceremony confidential, said the brief CCTV item.

    Three cordon fences circled the stadium, better known as the Bird's Nest for its unique structure of interwoven steel beams. Armed police only unlocked the gates for vehicles with special passes, according to the TV footage.

    Workers were still putting finishing touches on the venue, which will be the center stage for both the opening and closing ceremonies of the Olympics and Paralympics.

    All of the workers on duty had signed agreements with the Beijing Olympic Organizing Committee (BOCOG) to keep what they saw confidential, according to BOCOG.

    Two directors of the ceremony, Wang Chaoge and Fan Yue, attended a media debut of the outdoor performance "Impression West Lake" in Beijing on Thursday.

    Wang disclosed that the elements of "Sichuan" and "Wenchuan" will be embodied in the opening ceremony in tribute to the Chinese spirit manifested after the devastating May 12 earthquake that hit southwest China's Sichuan Province.

    He said the biggest headache for the organizers of the ceremonies was the weather.

    "It is the one thing beyond human control. Rain would cause delays in the progress of the event, as it would dampen performers' costumes and props," Wang said.

    Zhang Yimou, director-in-chief of the ceremony, said at the one-month countdown to the Games on Tuesday that all the crew worked at night to better adjust themselves to the evening performance. They took an oath on the countdown to struggle hard for a successful event.

    Zhang's team made three years of preparations for the show, which is expected by Chinese to showcase the essence of China's rich culture, concept and vision to the world.

    Sources with the team said there would be three more rehearsals of the opening ceremony.