Google will open a research and development centre in Shanghai, stepping up its effort to build a bigger search business in China.

Google has struggled in China to create the dominance it enjoys elsewhere in the world. It took 19 percent of the country's search market revenue in the first quarter, compared with 57 percent for market leader Baidu.com, according to Analysys, a telecom research and consulting company.

A spokeswoman for Google in China, Marsha Wang, confirmed the plans for an R&D lab today. She declined to say how many people it will employ or provide other details.

Google and its US rivals, Yahoo and Microsoft, have faced political difficulties in China, for agreeing to censor search results. In addition, their services are sometimes hard to access from inside the country. Yahoo's Flickr division said this week that its service was being blocked in China.