The global market research group, which currently has interactive research divisions in North America, Asia Pacific and EMEA, said it was extending the offering to Latin America by promoting Trixie Cartwright to regional director.
Cartwright, who will be based in Buenos Aires, joined TNS four years ago and will be moving from her London-based role of research director for TNS Global Interactive to oversee the regional division's launch.
TNS said that extending its services into South America was a natural development for the group and followed substantial growth in interactive research globally, particularly in emerging markets.
Mark Walton, TNS regional director for interactive research in Asia Pacific, said: "We have been assessing online opportunities in Latin America for some time and have conducted a number of successful tests there.
"These have confirmed not only the benefits of speed and cost efficiency, but also that the internet is becoming increasingly the most reliable and effective method of reaching many target audiences."