Chinese Vice Premier Wang Yang delivers a keynote speech at the International Investment Forum 2014 held in Xiamen, southeast China's Fujian Province, Sept. 8, 2014. (Xinhua/Jiang Kehong)

XIAMEN, Sept. 8  -- Chinese vice premier Wang Yang reiterated on Monday that the country will stick to its opening-up policy and continue to welcome foreign investment.

"The opening-up principle will stay unchanged for a long time, the investment cooperation framework become increasingly accommodative, and the law enforcement non-discriminatory," Wang said in a speech to the 18th China International Fair for Investment and Trade.

Acknowledging the important contributions foreign firms have made to China's development in the past 30 years, Wang said China is not to ignore their roles, to say nothing of rejecting them, in the new growth period.

"We will further ease market threshold for foreign investments, and focus on pushing the opening-up in the service industry," Wang pledged.

While meeting with representatives from some multi-national companies, Wang pointed out that instead of fixating on China's favorable policies, foreign businesses should value a fair market and legal environment more.

The remarks came amid concerns that China's attitude towards foreign firms may be changing following its anti-corruption probe against GlaxoSmithKline (GSK), and anti-monopoly investigations against top global brands such as Microsoft, Jaguar Land Rover, and Qualcomm.

In a clarification of such probes, Wang said the moves will bring a fairer, non-discriminatory business environment that helps to pave way for further opening-up.

The 18th China International Fair for Investment and Trade, which attracted 932 delegations from 110 countries and regions, kicked off on Monday in southeastern coastal city of Xiamen.

The four-day event, sponsored by the Ministry of Commerce, is a platform for both domestic and overseas participants to cooperate and explore business opportunities.