The complex's trees are falling over

"The ground at the Angkor complex has become soft ... and trees have collapsed and damaged some parts of the temples," said Oung Von, chief of the Angkor Conservation Centre.

"I am very worried that these old trees will destroy our national heritage site at the Angkor complex."

The site, which features on the Cambodian flag is believed to be the largest religious structure in the world. Most of the temples date from the 9th-12th centuries.

Some of the trees in the complex are 200 years old, and their roots form an intricate network under the site which supports many of the temples.

Film

Cambodia is suffering its worst flooding in decades, but officials say problems have been exacerbated at Angkor Wat because the site's old sewage system is clogged up meaning rainwater cannot drain away.

The temple is Cambodia's main tourist attraction

Reports said the roof of one temple had caved in after it was hit by a tree and walls had been knocked down in other temples.

Oung Von called on international donors to provide more help to protect Cambodia's Khmer heritage, which is also its biggest tourist attraction.

He said only 30% of the Angkor temples were being preserved despite help from 10 international organisations.

Last week it was announced that the temples are to be used as the backdrop for some of the scenes in the new action film Tomb Raider.

The Cambodian authorities have given permission for Paramount Pictures to use the temples as long as no guns are fired there.