Authorities in Hong Kong stepped up customs checks at the weekend to stamp out poultry smuggling after a truck driver was found infected by the H5N1 bird flu virus across the border in mainland China.

More officers were deployed at Hong Kong´s four land border checkpoints and the territory beefed up examination of suspicious cargoes and baggage at sea and air boundaries.

"We confiscated three fresh chickens and three fresh ducks by Saturday night at Lowu," a government spokeswoman said on Sunday.

"Five people tried to bring them in, four of them were mainland Chinese and one a Hong Kong resident."

The new effort, codenamed "Operation Parrot", began on Saturday.

Lowu is one of the heaviest land border crossings in the world, handling up to 17,000 people an hour during peak periods.

The spokeswoman did not know if the five people had been charged.

It is an offence to bring any meat or poultry into Hong Kong without an official certificate and offenders face a maximum penalty of HK$50,000 ($6,400) and six months´ jail.

Hong Kong suspended imports of live poultry from mainland China on Friday after the truck driver was confirmed to be infected with the H5N1 virus.

The 31-year-old driver lives in Shenzhen, just over the border from Hong Kong. It is unclear how he came to be infected although he went shopping at a wet market where live poultry was sold a few days before he fell ill.

He also ate a chicken which his wife prepared.

China says there has been no outbreak of the disease in poultry in Shenzhen. Chickens are chiefly responsible for spreading the virus to people.

The H5N1 virus has killed 129 people in nine countries since late 2003, most of them in Asia and including 12 in China, and experts have warned of a pandemic once the virus is able to spread easily among people.