Sir Martin Sorrell is eyeing up Aegis

Its announcement came as French firm Publicis said it would not proceed with a �1.57bn bid for Aegis after expressing its interest last month.

WPP said it was in discussions with an unnamed private equity firm about the possibility of a cash offer for Aegis.

Aegis-owned companies specialise in buying advertising space and planning marketing campaigns for their clients.

Feasibility study

WPP, led by chief executive Sir Martin Sorrell, is one of the world's three largest marketing services businesses.

In a statement, WPP said it was primarily interested in acquiring Synovate - Aegis' market research business.

There can be no assurance any offer will be made. WPP

"WPP confirms that it is in discussions with a private equity partner to explore the feasibility of a cash offer for Aegis," it noted.

"There can be no assurance any offer will be made."

Industry speculation has suggested that WPP could team up with US firm Hellman & Friedman.

Other suitors

Publicis revealed on Friday that it had decided not to bid for Aegis, saying it was not in the best interest of its shareholders.

However, the company added that it reserved the right to review its options should another firm make a firm bid for Aegis.

Takeover speculation surrounding Aegis has prompted frenetic buying in its shares recent days.

French businessman Vincent Bollore increased his stake in Aegis to 15% on Thursday. Mr Bollore, chairman of rival French marketing firm Havas, is also considered a potential suitor.

However, shares in Aegis closed down almost 4% at 132.50 pence on Friday on speculation that Publicis was set to withdraw its interest.

WPP shares dipped 0.5% to 552.50p.