Shanghai has reported another death from H7N9 bird flu, the local government said, bringing the total number of fatalities nationwide to at least 40.

A 56-year-old man, the husband of an earlier victim, died on Wednesday, the Shanghai government said. He had been hospitalised since April.

The Shanghai couple was believed to be a rare "family cluster" in which relatives can infect each other through prolonged, close contact.

But Chinese health authorities and the World Health Organization have said there was no evidence of human-to-human transmission in China with the source of infection believed to be poultry.

As of May 31, mainland China had reported 131 confirmed cases, the National Health and Family Planning Commission said in the latest figures released earlier this month. The death toll was 39.

China will announce official statistics for June next month.

The H7N9 bird flu outbreak that hit China this year had killed over a third of hospitalised patients, researchers wrote in The Lancet medical journal this month.