Rat meat is a favourite at weddings

The province of Bac Lieu alone is reported to supply more than 100 tonnes a day to the two countries' dinner tables.

In a region where farm labour pays as little as $1 a day, rat-catchers are making between 30 and 40 cents a kilo from about 50 specialist distributors.

In the single province of Bac Lieu there are now estimated to be as many as 2,000 full-time rat catchers.

Eating their predators

But environmentalists have pointed out that the reason the farmers are battling with so many rodents in the first place is due to the increasingly exotic tastes they are pandering to.

They say that adventurous diners have already munched their way through much of the snake population which used to keep the rats at bay.

Indeed the Vietnamese Prime Minister, Phan Van Khai, has banned the consumption or export of the rats' natural predators - snakes and cats.

Hundreds of hectares of the country's rice have been destroyed by rats.