The World Health Organization has said that there was no sign of `sustained human-to-human transmission` of the H7N9 virus in China.

The UN health organisation, however, said that it was important to check on 400 people who had been in close contact with the 14 confirmed cases.

WHO spokesman Gregory Hartl told a news briefing in Geneva that they have 14 cases in a large geographical area, and have no sign of any epidemiological linkage between the confirmed cases, and we have no sign of sustained human-to-human transmission.

The 400 contacts are being followed up to see if any of them do have the virus, have had it from someone else, he added.

Meanwhile, Chinese authorities slaughtered over 20,000 birds on Friday at a poultry market in Shanghai, Fox News reports.

The move came as the death toll from the new strain of bird flu mounted to six, spreading concern overseas and sparking a sell-off on Hong Kong`s share market.