German market researcher Gfk has withdrawn from the race to take over Taylor Nelson Sofres (TNS) in the UK after talks with private equity group Apax fell through.

The move has left advertising company WPP Group, headed up by chief executive officer Sir Martin Sorrell, as the sole bidder for TNS, The Independent has reported.

Gfk had initially been in discussions for a nil-premium merger with TNS when a formal bid was lodged by WPP in July – forcing Gfk to look at options for launching its own offer.

In seeking financial backing, Gfk turned to Apax, who pulled out of negotiations after failing to guarantee the degree of corporate control it was aiming for while also experiencing difficulty in garnering shareholder support, sources told The Independent.

WPP's offer of 0.1889 of its shares plus £1.73 (€2.16) cash, or around £2.69 (€3.37) per share at current prices, is seen as an unsatisfactory offer in the eyes of TNS chairman Donald Bryden. 'The board is completely clear in that our advice to shareholders is not to accept (the offer),' he said.