A total of 72 people died from the H7N9 bird flu strain in China in the first two months of this year, government figures showed, far more than in the whole of 2013.

China reported 41 deaths and 99 cases of H7N9 avian influenza in February alone, the National Health and Family Planning Commission said in monthly figures for infectious disease, bringing the total cases this year to 226.

The Asian country recorded 46 deaths and 144 cases for 2013 in an outbreak which started early in the year and returned in the autumn.

Chinese officials and the World Health Organization (WHO) say there is no evidence of sustained human-to-human transmission but there have been "family clusters" -- involving relatives in close contact apparently infecting each other -- since the new strain appeared in people last year.

The virus ignited fears that it could possibly mutate to become easily transmissible between people, which might threaten to trigger a global pandemic.

Experts have pointed to a seasonal rise in cases so far this year, thought to be linked to cold weather.

"It's largely a seasonal weather change thing and nothing else," the WHO representative in China, Bernhard Schwartlander, told reporters late last month.

"The virus just likes to be in the cold -- it survives more easily. Also in the wintertime the (human) respiratory system is a little bit more fragile," he said.

China has responded to the current outbreak by clamping down on live poultry markets and stepping up monitoring of people with symptoms associated with the virus.

Last week Hong Kong confirmed its sixth case of H7N9 bird flu, and the special administrative region of China has banned live poultry imports from the mainland in an effort to control the disease.