BEIJING - A total of 45.73 million migrant workers have joined China's urban workers' medical insurance system, the country's top economic planner, the National Development and Reform Commission (NDRC), said in a report Wednesday.

The medical insurance system in cities and towns now covers 424 million Chinese residents as of the end of October, NDRC director Zhang Ping said in the report on health care reform.

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Zhang delivered the report to the 18th session of the Standing Committee of the 11th National People's Congress (NPC), a bimonthly session that began December 20 and will end December 25.

China adopted its reform and opening-up policy in 1978. Farmers' large-scale migration to cities for work began in 1992 amid the nation's drive for a market economy.

The number of migrants soared from 60 million in 1992 to 120 million in 2003 and 220 million in 2009, according to official statistics.

According to Zhang's report, about 835 million rural Chinese, about 90 percent of the rural population, had joined the New Rural Cooperative Medical Care System (NCMS), a medical insurance scheme for villagers, by the end of October.

The central government has injected 50.9 billion yuan ($7.6 billion) into the medical insurance system to cover 6 million retirees from bankrupt state-owned companies, said Zhang.

College students are also covered by the urban medical insurance system, Zhang added.

Under the medical insurance system, governments in urban and rural areas this year paid no less than 120 yuan per person per year in subsidies, with about 60 to 75 percent of in-patient medical expenses being reimbursed, the report said.

Thanks to the government's health care reforms, some 51 percent of medical clinics in rural Chinese townships and small urban communities offer essential medications at low prices, Zhang said.

China spent 443.9 billion yuan on health care this year, with most of it used to promote system reform, he added.

Treatment of minor ailments has been increasingly included in the medical insurance system, he added.

"To make the payment of medical expenses convenient, the government is promoting the use of a one-card system, which help patients get reimbursed as soon as possible," Zhang told lawmakers.

Zhang added that the government will further expand the coverage of the medical insurance system and upgrade the quality of medical care services in 2011.