Despite record sales of vehicles in China, General Motors Co has posted a 14 percent drop in first-quarter profits, faced with one-off costs and weaker earnings in its core North American market.

Chairman and CEO Daniel Akerson told analysts on a conference call after Thursday's earnings release that the Detroit-based GM, which had 15.2 percent of the Chinese market during the January-March quarter, expects to invest at least $11 billion in China between 2013 and 2016, adding four assembly plants and raising capacity by 30 percent to 5 million vehicles.

It will boost capacity in the country 20 percent this year from a year ago, Akerson added.