The one week trip will be conducted by senior officials from the World Health Organisation and scientists from the Centre for Disease Control in Atlanta, as well as officials from Beijing and Hong Kong.

They will visit hospitals, poultry farms and markets, particularly those near the border with Hong Kong, looking for traces of the bird flu virus. Until imports were stopped in December, farms in mainland China supplied about 75,000 chickens a day to Hong Kong.

When bird flu appeared in the territory, concern was expressed that the virus could have originated in China, although officials in Guangdong deny finding any evidence of the virus. Local newspapers reported on Thursday that some members of the international team had been denied visas for the trip, but authorities in Beijing said all the delegates were welcome.

Hong Kong officials have now declared an end to the high-risk period for the virus, because no new infections have been found since the slaughter of the territory's chickens two weeks ago - a measure designed to stop the spread of the flu. But the death toll of those infected before the chicken slaughter has slowly risen.