China's economy must open wider to the world to fuel national growth, President Xi Jinping said, as the country's reformers vowed to gradually loosen a "negative list" regulating foreign market access.

China has repeatedly pledged to slacken restrictions on its manufacturing and service sectors as it tries to improve inefficient state-owned firms by adopting market-friendly policies to stave off slowing growth.

The world's second-largest economy, which grew 7 percent in the first half from a year earlier, is headed for its slowest economic expansion in 25 years in 2015.

"China should make unswerving efforts to attract foreign investment and foreign technology, and improve the mechanism for the country's opening up," the official Xinhua news agency cited Xi as saying at a meeting of the Central Leading Group for Deepening Overall Reform.

"Implementing a market access negative list system has great significance in releasing the decisive role of the market in allocating resources and further developing the role of government, and in establishing a commercial environment based on rule of law and building a new open-style economic system," Xinhua said, citing a statement from the reform group.

"The country will gain experience and gradually improve the list through pilot programs," the news agency said, citing the statement.

Business groups have expressed only tepid approval of such piecemeal pilot programs, arguing that many sectors currently off limits to foreign investors should be opened up nationwide instead of in select regions or zones.

Regulators issued a negative list of prohibited and restricted industries for foreign investors in March, though business lobbies have said it is too broad.

The list, issued jointly by the National Development and Reform Commission and the Commerce Ministry left prohibitions on foreign investment in 36 sectors, while 38 sectors were restricted.

China's government plans to reform state-owned enterprises but has been reluctant to cede too much control over industries it deems central to national interests.