China's health ministry Thursday reported a rise of about 22 percent in human immunodeficiency virus (HIV) infection and full blown AIDS this year and raised the estimated figure of the infected to 700,000.
The ministry said 223,501 people had tested positive for HIV by the end of October. Some 70,000 people have already developed AIDS.
"Sexual transmission is now the main mode for the spread of HIV, with an estimated 45 percent of new infections taking place through heterosexual transmission," the ministry said in a statement.
Reported cases also rose 30 percent last year, but UN experts have said the recent increases do not necessarily reflect a jump in new HIV/AIDS infections in China.
The recent drive to test more members of vulnerable groups may be an important factor behind the rise in reported cases, they say.
Most HIV infections are believed to be still undiagnosed because of ignorance, fear, poverty and other factors.
"Currently, China's HIV epidemic remains one of low prevalence overall, but with pockets of high infection among specific sub-populations and in some localities," the ministry statement said.
The ministry warned that the spread of HIV/AIDS in China "continues to be driven by high-risk behaviour within particular sub-populations".
The virus has been spreading from high-risk groups to the general population because of unsafe sex and the migration of people already infected.
Thursday's statement said an estimated 42 percent of new infections were through intravenous drug use and 12 percent were through homosexual transmission.
About 71 percent of the newly infected were men, it said.
Under pressure from the UN, China has become more open about HIV/AIDS issues in recent years.