LONDON, May 23 (Reuters) - GlaxoSmithKline Plc (GSK.L: Quote, Profile , Research) is set to unveil plans for major research and development centre in China, joining a growing number of pharmaceutical companies tapping into the country's skillbase in life sciences.

Research head Moncef Slaoui told the annual meeting of Europe's biggest drugmaker on Wednesday that an announcement on the investment in a fully integrated research and development facility was imminent.

People familiar with the situation said it could come as early as Thursday, following approval by Glaxo's board this week.

The move will add to Glaxo's diversification of R&D, which also includes work in emerging market countries such as India and Croatia.

"We think it is going to be transformational to our R&D activity," Slaoui said. "There is a huge qualitative as well as quantitative asset in China."

The Glaxo facility will cover not just niche aspects of research but the full range of activities from drug discovery to final development of approvable new medicines, he added.

The move reflects the rapidly growing importance of China in the pharmaceutical landscape -- as a centre for research, production and future sales.

China is set to become the world's fifth-largest medicine pharmaceuticals market by 2010, with sales nearly doubling to $25 billion from $13 billion in 2005, Boston Consultancy, an independent consulting group, said last year.

In the past Western drugmakers have been wary of investing in China because of a reputation for weak patent protection. But industry executives say patent enforcement is improving.

Other major drug companies with a research presence in China include Novartis AG, AstraZeneca Plc, Pfizer Inc. and Roche Holding AG.