Secretary for Food & Health Dr York Chow today scaled down the response level for avian influenza from 'serious' to 'alert'.

The Government raised the level after detection of the H5 avian influenza virus among chickens in a Yuen Long farm on December 9.

The Food & Health Bureau later formed an investigation group on epidemiological study. The group suggested in March chicken farms improve their biosecurity measures.

The index farm adopted improvement measures and the sentinel chickens there passed tests for the H5 virus, leading the Agriculture, Fisheries & Conservation Department to lift the ban on the farm last week.

Samples collected from chickens at farms, the wholesale market and retail outlets since December 10 have all tested negative for the H5 virus.