Aegis is to pay a total cash consideration of £4m, payable over three years and subject to strict performance criteria.
The business will be integrated into Synovate's worldwide network, which in September helped Aegis boost its profits to £36.9m in the first half of 2005 with organic growth of 12.2%, double the market growth.
The market for research in Turkey, with a population of 73m, is expected to grow by 15% this year. Plus Remark has established expertise across the financial services, consumer goods, automotive, industrial products, IT, telecoms and media markets.
Robert Lerwill, Aegis chief executive, said: "Plus Remark fits very neatly into Synovate's geographic footprint, and takes us into an important new market.
"This will help Synovate's existing clients, while our new clients will get access to all of Synovate's services elsewhere in the world. Synovate already has above-industry exposure to today's fastest-growing research markets; today's addition will only enhance that."
It is the second acquisition Aegis has made in recent months. In October, Synovate bought youth marketing agency the Filter Group in Asia to form the basis of its youth research offering in the region feeding into its global division Synovate YC.
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