Surin Pitsuwan, secretary-general of the ASEAN, said that China and these countries are building the biggest free trade zone in the world that comprises nearly 1.9 billion people.

The 5th China-ASEAN Expo opens in Nanning on Wednesday. [Xinhua]

The Expo was proposed by Chinese Premier Wen Jiabao five years ago. The 10 ASEAN countries are Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam with a total area of 4.5 million square kilometers, whose economies were seriously hurt by the financial crisis in 1997.

As the largest developing country in the world, China should step up cooperation with the ASEAN countries in light of the uncertainty of the world economy, said Chinese Commerce Minister Chen Deming.