Reported cases of HIV and AIDS in China has jumped 30 percent this year, with intravenous drug use the main source of infection, Chinese state media said Tuesday.

The reported number of cases has grown to more than 183,000 this year, up from 144,000 at the end of last year, the China Daily newspaper reported, citing figures from the Ministry of Health.

Of the reported cases, more than 40,000 have developed into AIDS, it said.

The newspaper said the spike in cases was due in part to better reporting by health officials and patients. It said that 37 percent of the cases reported this year were linked to drug use and 28 percent were caused by unsafe sex.

It said 5 percent were caused by people selling blood illegally or receiving infected blood from hospitals. The report didn't say what caused the remaining 30 percent of infections.

Experts say China has hundreds of thousands people infected with HIV who don't know it or choose not to report it. At the end of last year, China and the U.N. estimated there were a total of 650,000 HIV cases in the country, including those that were unreported.