China has defended its export policies after the United States and European Union complained to the World Trade Organisation (WTO) they violated international trade rules.

The US and EU claim China's restrictions on the export of commodities including silicon, coke and zinc, give Chinese manufacturers an unfair advantage over international competitors.

But Beijing said on Wednesday its policies were designed to "protect the environment and natural resources".

"China believes the policies in question are in keeping with WTO rules," the Chinese ministry of commerce said in a statement.

If the complaints by the US and EU are not resolved within the next 60 days, the pair can formally request a WTO hearing - a process that can take up to a year.

If the outcome is in their favour and China still refuses to lift its export restrictions, the two would be given permission to impose economic sanctions on China.

Failed negotiations

The US took its case to the WTO after more than two years of negotiations with China failed.

The trade row signifies a sharp deterioration in relations between the US and China [EPA]

Ron Kirk, the US trade representative, said China's actions were endangering US jobs.

"The United States believes that China is unfairly restricting exports of raw materials,'' he said.

"These actions are hurting American steel, aluminum and chemical manufacturers, among other industries, that desperately need these materials to make their products.''

Analysts expect the fight will be just one of many trade cases the administration of Barack Obama, the US president, files against the country.

Obama made campaign pledges to take a tougher approach with US trading partners in the face of soaring job losses and the longest recession since second world war.