Beijing, Apr 15 (IANS/RIA Novosti): Russia is preparing to enhance sanitary control measures in case the bird flu situation in China deteriorates.

"The World Health Organisation (WHO) has not yet given recommendations for quarantine, and we are not introducing prohibitive measures now, but simply paying increased attention [to the issue]," Russia's chief sanitary doctor Gennady Onishchenko said Sunday.

"But if the process spreads, we will enhance the appropriate measures in this situation."

China reported 11 fresh cases of infection of H7N9 avian flu Sunday, bringing the total number of reported cases to 60.

Thirteen people have died from the disease since last month. The state-media reported the latest two deaths were reported in Shanghai.

"We still cannot understand the mechanism of the disease as there is practically no contact with poultry in big cities," the Russian official said.

"H7N9 has always been transmitted to humans through birds, and we need to study the [problem] seriously."

Chinese health authorities have so far treated the infections as isolated cases and ruled out human-to-human transmission.

A fresh report by a team of Chinese experts, published in the New England Journal of Medicine, indicates H7N9 causes unusually severe respiratory infection, sepsis and brain damage, and appears to be resistant to vaccination and treatment.