China has almost completed its investigations into solar-grade polysilicon from the United States, the European Union and South Korea, but the timing of announcing the preliminary rulings depends on the EU's decision on whether to impose punitive duties on Chinese-made solar panels, experts said.

"The investigations have been near their conclusion for quite some time," said a source with the Ministry of Commerce.

On July 20, the ministry launched anti-dumping and anti-subsidy investigations into solar-grade polysilicon, an ingredient in solar panels, imported from the US, and an anti-dumping investigation into the material from South Korea.

On Nov 1, the ministry launched anti-dumping and anti-subsidy investigations into the same product from the EU.

Another probe was launched on Nov 26 to determine whether retroactive duties should be levied on the material from the three sources.

The ministry delayed the publication of its preliminary rulings to June. Meanwhile, the European Commission is reported to be planning punitive tariffs ranging from 37.3 percent to 67.9 percent on solar panels from China.

The Brussels-based commission launched its anti-dumping probe into Chinese-made solar panels on Sept 6 and added the anti-subsidy investigation on Nov 8. The commission is expected to issue the preliminary ruling of the anti-dumping probe by June 6, and that for the anti-subsidy probe by Aug 8.

"China's announcement of the preliminary rulings of the trade investigations is behind schedule, but the Ministry of Commerce is probably waiting for the EU's official rulings of the solar panel investigations," said a deputy director surnamed Zhang from the China Chamber of Commerce for Import and Export of Machinery and Electronic Products.

"We have to wait for the government to announce the final decision on the polysilicon case and there is no timetable now," said Li Junfeng, deputy director of the Energy Research Institute under the National Development and Reform Commission.

He added that he has been opposed to a trade war since the very beginning when the US started anti-dumping and anti-subsidies probes into solar panels imported from China, but "we have to make our move when others fight us in the first place".

The 21st Century Business Herald quoted unnamed sources on Wednesday as saying that China will start to levy punitive duties on polysilicon manufacturers from the US, the EU and South Korea at the end of May and, according to the draft plan of the preliminary rulings, the heaviest tariffs will be imposed on US manufacturers.

Ministry of Commerce spokesman Yao Jian said on May 9 that China firmly opposes the EU's tariffs on the nation's solar exports and will defend the interests of Chinese companies if the EU insists on the measures.

Sun Guangbin, secretary-general of the chamber's solar division, told the first Global Solar Summit in Italy on May 8: "If solar panel exports from China are impeded, this will impact on the costs of European products. Nevertheless, we are willing to cooperate and maintain a dialogue in order to bring our production in line with market demand."

Gao Jifan, chairman and chief executive officer of Trina Solar Ltd, speaking on Monday at a solar industry exhibition in Shanghai, said: "Solar companies from the Europe, Asia and the US have their different strengths and advantages in the industrial chain. Companies from different countries should improve the healthy development of the solar industry through cooperation."

He said all players in the global solar industry should abide by international regulations and conduct their businesses under open and fair market rules.