Residents of a Chinese city were ordered to cull all their poultry as authorities stepped up attempts to halt the spread of the deadly H7N9 bird flu, state media reported Thursday.

Thousands of birds and livestock were slaughtered by the Tuesday midnight deadline in Nanjing, in the eastern province of Jiangsu, the China Daily said.

The number of cases of the H7N9 strain of avian influenza rose to 33 on Wednesday, with nine deaths since China announced over a week ago that it had been found in humans for the first time.

Residents who did not comply with the regulation in Nanjing would fined up to 50 yuan ($8), the China Daily said, adding that local officials offered help to kill birds and animals, with more than 2,000 dispatched by the authorities.

The newspaper also indirectly quoted an agricultural official in Beijing saying that the measure "goes too far and could cause panic".

Shanghai has culled more than 111,000 birds, banned trading in live poultry and shut markets in a bid to curb the outbreak.

Nanjing and the city of Suzhou followed suit with bans on live poultry trade, while Hangzhou culled poultry after discovering infected quail.

In China poultry is often bought live from markets and taken home before being slaughtered, cooked and eaten.

Meanwhile, the state-run Global Times reported Thursday that anti-bird nets were being erected in poultry farms in Beijing to prevent possible avian flu infection from migrant birds.

"With the weather getting warmer, migrant birds are back now but there is still not enough food for them in Beijing," the newspaper quoted a spokesman for Beijing Infectious Animal Plague Prevention Office as saying.

"It is possible that they will seek food in open poultry farms with free range poultry. If there are H7N9 carriers, other birds might get infected and that is why we made this decision," the official added.