Lowe embroiled in poaching row with Interpublic

The advertising veteran Sir Frank Lowe threatened legal action against his former employer Interpublic yesterday over its claims he violated his contract by poaching staff and clients for his new agency.

Sir Frank issued a furious riposte to Interpublic's claims, demanding an "immediate withdrawal" of the allegations and an "unreserved apology." He said: "The allegations are without foundation and are utterly refuted. If Interpublic does not withdraw its baseless claims we may seek damages for defamation and tortious interference."

The move came as David Hackworthy resigned as chief strategy officer of DDB London, part of the Omnicom group. He is expected to join Sir Frank's new firm. Another advertising executive, Mark Cadman, a managing director of JWT London, part of the WPP group, is also rumoured to be joining.

On Friday, Interpublic, the global marketing and advertising giant, started legal proceedings against Sir Frank, one of its former directors, for "violation of contractual and fiduciary duties". The group, which owns Lowe Worldwide, the advertising agency co-founded by Sir Frank, is pursuing the claims at the American Arbitration Association in New York and is understood to be seeking substantial damages.

Interpublic has accused Sir Frank of using confidential and proprietary information, gained when he was head of Lowe, to set up his own agency, which in December poached the Tesco account - worth about £6m a year. He has recruited Paul Weinberger, previously the chairman of Lowe London, alongside two members of the creative team on the Tesco account - Sam Cartmell and Jason Lawes. The executive creative director Ed Morris is also poised to leave Lowe to join Sir Frank.

Interpublic said it would hold any Lowe employee seeking to join Sir Frank to their full notice period.

Sir Frank sold Lowe to Interpublic in 1990 and spent more than a decade with the group before retiring as head of Lowe in 2003. He then acted as a consultant and agreed not to approach clients or employees for two years. That period is up but Interpublic is understood to be unhappy about his actions because it is still paying him a sizeable retirement package.

The loss of Tesco, Lowe's biggest client, came at a bad time for the agency, which has recently lost work from clients including HSBC and Unilever.

Paul Hammersley, the chief executive of Sir Frank's as yet unnamed new agency, joined from DDB London but previously spent a decade at Lowe. He said: "We are concentrating on getting the business up and running to focus on Tesco."

Mr Hammersley said a name for the agency, which will be based in Soho, London, from early March, would be announced by the end of this week.