UPDATE 2-Security group G4S eyes expansion, sales grow

* 9-month op profit up 12 pct, margins up 0.2 pct

* To enter Brazil, expand in China after law change

* Has around 45 mln stg left for acquisitions in 09

* Shares down 0.6 pct

(Adds company, analyst comment, shares, details)

By Rhys Jones

LONDON, Nov 9 (Reuters) - G4S (GFS.L), the world's biggest security firm, said nine-month sales were boosted by demand in emerging economies and increased government spend, and it planned to boost operations in both China and Brazil.

The company, formed from the 2004 merger between Denmark's Group 4 and Britain's Securicor, said operating profit was up 12 percent on sales up 9 percent for the nine months to the end of September, without giving specific figures.

G4S, which supplies security guards and other safety-related services to firms in over 100 countries, added that margins rose 0.2 percent in the period.