China is paying close attention to recent investigation launched by the US against steel and aluminum imports and calls for free and open international trade system, the Ministry of Commerce said on Thursday.

The United States launched a probe into whether imports of Chinese steel are a national security threat. A rarely used legal tool, known as Section 232 investigation, was invoked to launch the probe.

Sun Jiwen, spokesperson with the ministry, said the term "national security" was too broad, and measures taken under it could easily be abused if there are no clearly defined conditions. "They would impede international trade flow," Sun said.

Building on the progress made by Sino-US 100-day action plan, China expects closer economic and trade ties with the US, Sun added.

The action plan was agreed upon by leaders of both countries in April, with a goal to establish a comprehensive economic dialogue.

"Overall, bilateral economic cooperation has achieved many positive results. China will continue to make efforts, but also hopes that the US side could work together toward this end," Sun said.

Furthermore, Sun called on all economies to support the free and open international trade system.

"Currently the world economy is still very fragile. China hopes that all countries will strengthen communication and seek cooperation so as to create a favorable environment to facilitate globe economy," Sun told a news conference on Thursday.

"We need to work together to resist trade protectionism and stay cautious against the application of any trade restrictions."