Live chicken sales resumed in markets across Hong Kong Wednesday after a 21-day ban on poultry imports and sales following a bird flu outbreak.

However, many chicken stalls remained closed because of tough new restrictions which prohibit the keeping of live poultry in markets overnight to lower the risk of a new bird flu outbreak.

Thousands of chickens were slaughtered when bird flu was discovered in samples taken from four markets in Hong Kong last month. The source of the infection was never traced.

The government tightened restrictions and announced a compensation package for poultry farmers and traders which has been the subject of weeks of wrangling.

Traders' groups estimated only around 100 of licensed 469 poultry stalls across the city of 6.9 million would reopen for business Wednesday while the government said it expected 180 to open.

Traders insisted the move was not a boycott but said they wanted to test market conditions before reopening, fearing they could be left with unsold chickens at the end of each day's business.

Up to 30,000 chickens from local farms and from farms across the border in mainland China were expected to be available for sale in markets Wednesday.

Hong Kong's health secretary York Chow appealed to traders to concentrate on getting business back to normal under the new restrictions rather than fight for higher compensation.

'It is important the trade should be more pragmatic and realistic rather than try to ask for anything more,' he told reporters.

Hong Kong was the scene of the first outbreak of bird flu to jump the species barrier in modern times in 1997 when six people died and 12 others were infected.

Tough new hygiene and monitoring controls have since been introduced and Hong Kong has been spared further human infections in the recent bird flu cases across the Asia region.