PARIS/LONDON, Sept 14 (Reuters) - Sanofi-Aventis has signed a research collaboration agreement with a Chinese institute in the cancer stem-cell field, becoming the latest big drugmaker to tap into China's growing life science skills.

The purpose of the agreement is to isolate acute myeloid leukaemia stem cells and generate monoclonal antibodies against these cells to help develop new therapies, the French pharmaceuticals group said on Friday.

The deal was struck with the Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences, Tianjin.

Qi-Min Zhan, head of research at the academy, said in a statement that China would "actively encourage many more such initiatives".

Sanofi's move reflects the rapidly growing importance of China in the pharmaceutical landscape -- as a centre for basic research, clinical trials, production and future sales.

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, and companies have been ramping up their presence.

China is set to become the world's fifth-largest 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.

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

Sanofi, the world's third-largest drugmaker, already has a significant commercial presence in China and is conducting many clinical trials in the country.

The French group is to give investors a detailed update on its research and development drug pipeline in Paris on Monday.