The company's interim results revealed that the firm recorded revenue of £460m in the six months to June 30, an increase of 3.1% on the first half of 2004, and a profit before tax of £35.9m.
TNS chief executive Mike Kirkham said that custom and syndicated research was particularly strong in mainland Europe and Asia. However, he added that the UK and US are performing less well.
"With the UK and US custom businesses performing less well, the group as a whole achieved underlying revenue growth of 2.5%," he said.
However, Kirkham is optimistic that TNS will perform better in the UK in the last six months of 2005.
"In both UK and US custom, we anticipate achieving a better performance in the second half," he said.
"We expect that Europe as a whole will maintain steady growth for the full year, but the Americas region is still expected to show a small decline. We anticipate that Asia Pacific will maintain its momentum in the second half and perform strongly for the year."
TNS is the world's second-largest market research company behind VNU.
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