PARIS, May 26(Xinhuanet) -- Paul Andreu, the architect of terminal 2E of Paris Charles de Gaulle airport, whose roof collapsed on Sunday morning, came back Tuesday to Paris from his work of China's National Grand Theater in Beijing.

He doesn't believe there was error in the design of the airport."I don't think I have made mistake in the design and the construction," he declared to French television TF1, adding that he was infinitely sorrowful for the death of the four victims in the accident.

He arrived in the accident site on Tuesday afternoon after cutting short his stay in Beijing. He said he was shocked by the collapse and was ready for the expertise to help investigate the cause of the accident.

Two investigations, one judicial and one administrative, have opened to determine whether the design, calculations, the construction or even the ground upon which it was built were at fault.

A 30-meter section of the 650-meter-long boarding and waiting area collapsed on Sunday morning, killing four passengers, including two Chinese, and injuring three others. It is one of the three main structures in the Terminal 2E complex that were opened on July 25, 2003.

According to the head of the airports authority (ADP), the terminal, which handled around 20,000 passengers a day, is closed indefinitely, and the whole building that cost 750 million euros (900 million dollars) may be demolished if a design flaw is believed to be the cause of the collapse.

Andreu, 65, an internationally-renowned architect, has designed more than 50 airports including the whole of Charles de Gaulle. His works brought him the nickname "architect of airports."

He left the ADP on November 30, 2002 for better concentrating himself in the construction of the Oriental Art Center in Shanghai and especially the National Grand Theater in Beijing near Tian' anmen Square.

The theater, whose construction started in 1999, has aroused many divergences on its incoherent form with its environments and the Chinese culture, and was then suspended for 18 months after a rare controversy in China on the project. Some others appreciate however its modern and outstanding design.

The initial budget for the Theater cost 2.7 billion yuan (324 million dollars). The final cost would be about 3 billion yuan, according to Andreu, who is also the architect of Pudong airport in Shanghai.