(Adds state agency comment, background)
SHANGHAI/HONG KONG, July 15 (Reuters) - A Chinese government agency that oversees state-owned firms on Tuesday named six of them it said will participate in a reform process that could widen the role private capital plays in China's massive state sector.
The six named companies are China National Building Materials Group; China National Pharmaceutical Group Corporation (Sinopharm); State Development & Investment Corp; China National Cereals, Oils and Foodstuffs Corp (COFCO); China Energy Conservation and Environmental Protection Group; and Xinxing Cathay International Group.
Two to three more companies will be selected for reforms, according to the State-owned Assets Supervision and Administration Commission of the State Council (SASAC), which is responsible for more than 100 of China's biggest state-owned enterprises (SOEs).
Some big state-owned enterprises (SOE) have listed subsidiaries, such as China National Building Material Co Ltd , Sinopharm Group Co Ltd and China Agri-Industries Holdings Ltd.
However, the overall role of private capital in the groups that control the bulk of economic activity has been small.
Tuesday's move is the latest by Beijing, which is carrying out its biggest overhaul of the bloated and debt-laden state-owned sector since the late 1990s.
SASAC said in a statement these companies were selected because they have undergone deeper reforms and seen better results in recent years.
The agency said one goal of the reform program is "to enhance the state-owned regulatory model by focusing more on capital management".
Large swathes of China's economy still lie in the hands of government-owned conglomerates, a situation President Xi Jinping promised to change last year by encouraging more private participation in such enterprises when he announced sweeping reforms to the country's socialist economy.
In March, Chinese Premier Li Keqiang said the telecoms, electricity, resource development, banking, oil and utilities sectors will be open to non-state capital.
In recent months, some of China's top conglomerates such as CITIC Group Corp, China's flagship investment company, have announced spin-offs and restructuring plans while local authorities have begun experimenting with new management structures.
Sinopec Corp , Asia's biggest oil refiner, announced in February a planned spin-off of part of its marketing arm that could raise up to $20 billion.
The last time there was a major reform and restructuring programme for state-owned enterprises, in the 1990s, the government sold off or shut thousands of firms, culling the number of state firms to about 110,000 from 260,000. (Reporting by Brenda Goh in SHANGHAI, Clare Jim and Yimou Lee in HONG KONG; Editing by Richard Borsuk)