WPP, the world's second largest advertising group, wants the Takeover Panel to force GfK, the German market research company with which it is vying for control of rival Taylor Nelson Sofres, to make clear whether its original financial backer is still in place.

WPP's chief executive Sir Martin Sorrell’s comments come amid concerns that GfK is trying to raise new finance to replace its original backer, which has not been named, or to supplement its contribution.

"GfK’s original statement regarding the financing of a bid for TNS should have been modified to clarify its situation," said a WPP spokesman.

WPP tried to split up an agreed nil-premium all-share merger between GFK and TNS earlier this year, with a higher hostile bid made up of cash and shares.

WPP, which today issued results for the six months to June 30, predicts that global financial markets will begin a path to recovery in mid 2009, although Britain will continue to be the advertising group’s slowest growth market.

The group, whose worldwide advertising agencies include Ogilvy & Mather and Young & Rubicam, reported better than expected like-for-like sales growth of 4.3 per cent for the first half, and raised its interim dividend by 20 per cent.

However, sales fell slightly in July, according to Sir Martin. “There was a slight slowdown in May and June. Since then it has been pretty much the same pattern. July followed a pretty similar pattern to the second quarter,” he said.

He added that, while the global economy could show signs of recovery in the middle of 2009, the effects will not be seen until early 2010. While the company did not lower its forecast of 16 per cent profit growth for 2009, it gave warning that the prospects for next year were "less certain" because of the slowdown in European and American economies, and a spurt in business from China that would drop off when the Olympics were over.

WPP said that Britain remained its slowest growing region, with revenues up 4.6 per cent. Continental Europe was up 4.8 per cent, slightly lower than the 5.2 per cent of the first quarter, with Central and Eastern Europe particularly strong at almost 20 per cent.

Asia Pacific, Latin America, Africa and the Middle East continues to be the group’s fastest growing region, with revenues up over 17 per cent. Mainland China and India continued the rapid growth seen in 2007 and the first quarter of 2008, with first half like-for-like revenues up more than 17 per cent. India grew at a rate of more than 30 per cent in the second quarter.

The markets of Asia Pacific, Latin America, Africa and the Middle East and Central and Eastern Europe accounted for over 25 per cent of the group's revenues in the first half, up from 23 per cent in the same period last year. WPP wants emerging markets to account for a third of group revenues.

The group said that 55 per cent of first-half revenues came from outside advertising and media investment management, compared with 53 per cent last year. The group is keen to increase this figure to two thirds of group revenue.

WPP said that spending on the United States presidential election campaign and around the Beijing Olympic Games should continue to boost 2008 revenues, adding that some of its clients take the view that “the cost of cutting brand spending at this stage of the cycle is too costly in the long term”.

First-half sales were £3.4 billion, beating analysts’ average predictions of £3.2 billion. Pre-tax profit for the six months rose by 15.1 per cent from £294.1 million to £338.5 million.

WPP’s share price rose 3.36% per cent to 491.5p.

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