BEIJING (AFP) - China on Monday unveiled its multi-million-dollar National Aquatic Stadium, a blue bubble-wrapped structure known as the "Water Cube", which will stage the swimming events at the August Olympics.

The Beijing venue, covered by a membrane of tough Teflon-like plastic that resembles bubbling water, took four years to build and cost a reported 200 million dollars, largely financed by donations from Chinese living overseas.

It stands close to another Beijing Olympic icon, the National Stadium or "Birds Nest", which is scheduled for completion in April or May.

"I am very moved and very proud," said Li Aiqing, president of Beijing's state-owned Asset Management Company which owns the Water Cube, at an inauguration ceremony.

"This was a very ambitious project in terms of the construction technology, and a most difficult construction challenge."

The eco-friendly structure's translucent shell allows in natural sunlight, providing heat and light and cutting energy use by up to 30 percent, according to the Beijing Olympics organising committee.

The 17,000-seater venue will host swimming, diving, synchronised swimming and water polo during the August 8-24 Games.

But its first event will be the six-day China Open, a swimming competition starting Thursday that will serve as a test of the venue.

Organisers have built or refurbished 37 venues, 31 of them in Beijing, to stage 28 sports during the Games.

More than half of Beijing's venues, including the Water Cube, are concentrated in a small area in the north of the city known as the Olympic Green.

Four other cities will host the football tournament, yachting will take place in the Yellow Sea port city of Qingdao and Hong Kong is to stage the equestrian events.