• by Joe Mandese  @mp_joemandese, December 27, 2007

Aegis Group's Isobar network, already the largest digital advertising services group in the world, just got bigger. Aegis this morning said it acquired Extenseo, the No. 1 search marketing agency in Belgium from Belgacom Skynet.

Aegis did not disclose the purchase price, but Extenseo, which was founded in 1998, has gross assets valued at $2 million.

Extenseo will become part of Isobar's already fast-growing search network, and will be re-branded as iProspect, a move that will expand Isobar's iProspect network to a total of 12 countries. Isobar acquired iProspect in 2003.

According to a recent report from RECMA, Isobar already is the world's largest interactive ad agency network, with 2,160 employees as of year-end 2006.