There has been no H5N1 outbreak in Hong Kong flocks since 2003.

The 'Fujian-like' strain could 'rapidly mutate', and monitoring was 'a must' so scientists could know how it was changing, said Leo Poon Lit-man, University of Hong Kong assistant professor of microbiology. A vaccine against the strain was also needed in case it triggered a flu pandemic, he said.

'I assume the Centre for Health Protection is communicating with [mainland authorities],' Professor Poon said.

Another bird flu expert, who did not wish to be named, said he would like to know how birds were found with Fujian-like viruses.

'Ask the government to explain,' this expert said.

A spokesman for the Agriculture, Fisheries and Conservation Department said that of 3,430 wild birds found dead in Hong Kong and tested for H5N1 this year, 15 had tested positive, all for the 'clade 2 subclade 3' strain of the virus.

A World Health Organisation spokesman said that was the same strain as the 'Fujian-like' strain identified in a scientific paper published in October by University of Hong Kong virologists Guan Yi and Malik Peiris and US flu expert Robert Webster, of St Jude's Children's Hospital in Memphis, Tennessee.

The researchers called it a new strain of the deadly H5N1, and said it had emerged in October 2005. The strain had been found in almost all poultry outbreaks and in some human cases in southern China, and had been detected in Hong Kong, Laos and Thailand, they said. And Professor Poon said yesterday: 'This virus can be found in other parts of China and basically in Asia.'

The researchers' paper caused controversy, with the Ministry of Agriculture in Beijing denying a new virus strain existed. The director of its veterinary bureau, Jia Youling , said data the researchers cited was false. 'There is no such thing as a new 'Fujian-like' virus variant at all,' he said in November.

A month later, WHO acting assistant director-general David Heymann said the strain had been circulating since 2005,and that the mainland had provided information and sequencing data about the strain. Last week the mainland reported its 15th human death from H5N1, a 16-year-old boy in eastern Anhui province . A spokesman for the Centre for Health Protection said the Ministry of Health in Beijing was investigating the case.

Mainland farms supply day-old chicks to replenish Hong Kong's poultry flocks. The Agriculture, Fisheries and Conservation Department spokesman said all the farms were in Guangdong.

Hong Kong has halted imports of live poultry and poultry meat from 13 provinces: Anhui, Fujian, Guizhou, Hubei, Hunan, Inner Mongolia, Jiangxi, Ningxia, Shanxi, Sichuan, Tibet, Xinjiang and Yunnan .

Wing and a prayer

15 birds have been found with Fujian-like H5N1 in Hong Kong so far this year

3 Scaly breasted munia

Jan 3 Leighton Road, Wan Chai

Feb 21 Sing Woo Rd/Wong Nai Chung Gap Rd, Happy Valley

Feb 27 Fu Cheong Estate, Sham Shui Po

1 Crested goshawk

Jan 12 Shek Kip Mei Health Centre, Sham Shui Po

2 House crow

Jan 17 Lai On Estate, Sham Shui Po

Jan 25 Yee Kok Crt, Sham Shui Po

1 Japanese white-eye

Jan 17 Kai Tak, Kowloon City

1 White-rumped munia

Jan 18 Boundary St, Kowloon City

1 Peregrine falcon

Jan 24 Chai Wan Kok St, Tsuen Wan

1 Blue magpie

Feb 7 Tai Po Rd, Sham Shui Po

2 Silver-eared mesia

Feb 9 Boundary St, Kowloon City

1 Common kestrel

Feb 17 Pak Tin Estate, Sham Shui Po

1 Chestnut munia

Feb 21 Prince Edward Rd West, Kowloon City

1 Long-tailed shrike

Mar 6 Harbourview Horizon, Hung Hom

Source: AFCD