China's Ministry of Commerce said Saturday it has decided to extend anti-dumping and anti-subsidy investigations into US-made off-road vehicles and sedans with an engine displacement of 2.0 liters and above.

The extension is for six months, until May 6, 2011, the ministry said in a statement on its website.

The ministry made the decision because the two cases are "special" and "complicated," the statement said without elaborating.

China launched the anti-dumping and anti-subsidy probes on Nov 6, 2009, after the China Association of Automobile Manufacturers complained that US carmakers had unfairly benefited from 31 government subsidy programs.