Industry veteran John Seifert has been appointed Ogilvy & Mather's new worldwide chief executive officer with immediate effect. He succeeds Miles Young who will continue as chairman until September this year, when Mr Seifert assumes that role.

Mr Seifert, 58, who has spent 37 years at Ogilvy & Mather, most recently as chairman and chief executive officer of its North American operations - a position he will retain - will partner Tham Khai Meng, the agency's worldwide chief creative officer who will also become co-chairman of the worldwide board, said the firm in a statement.

Mr Seifert's leadership in North America over the past seven years has resulted in a reinvigoration of the region, substantial revenue growth, digital excellence and impactful talent recruitment. This new appointment ensures continuity of leadership for Ogilvy & Mather, said the agency.

Mr Young, who will retain a non-executive role and continue to work with Ogilvy & Mather and parent company WPP on key global clients, said: "John Seifert is truly an exemplary Ogilvy citizen. His values and the brand's values are indistinguishable. And if you talk to his clients you will find a fan club united in admiration of him."

Before assuming leadership of Ogilvy & Mather North America, Mr Seifert was responsible for a portfolio of 25 global clients totalling nearly $1 billion in revenue. He has worked throughout the agency's worldwide network in client leadership and general management positions in Los Angeles, Chicago, Bangkok, and Singapore.