Discovery of a deadly new strain of bridflu has led to the temporary closure of Hong Kong's only live poultry market and led authorities to cull 20,000 birds in a bid to control the disease.

Although H7N9, which has infected 96 people since the beginning of the year, is only known to have passed from one human to another on one occasion (the rest of the infections were from direct contact between humans and infected poultry), it has proven fatal in 19 of these cases. The disease is "an unusually dangerous virus for humans," according to the WHO.

In all there have been over 200 confirmed cases of the virus in humans. So far, all reported cases of H7N9 have been in China, Hong Kong and Taiwan.

In Eastern China, sale of live poultry has been banned in the hope of stemming the spread of disease. Earlier in the month, the UN Food and Agriculture Organisation (FAO) warned that movements of people and poultry over the Chinese New Year period are likely to lead to an increase in cases of the disease.

Hong Kong authorities suspended imports of live chickens form the Chinese mainland after the discovery of H7N9 in birds imported from Guangdong province on Tuesday.