Singaporean advertising veteran Tham Khai Meng was fired on Wednesday from his long-time position as worldwide chief creative officer of the Ogilvy Group.
The global advertising agency's chief executive officer John Seifert told employees in a memo that this followed an internal investigation into complaints over Mr Tham's behaviour.
The complaints surfaced two weeks ago and were serious enough that an external legal counsel was appointed to investigate the matter, said the memo.
"After carefully reviewing the investigation's findings with several of my partners, we concluded that Khai's behaviour was a clear breach of our company values and code of conduct," Mr Seifert wrote.
"I have decided to terminate Khai's employment with the company with immediate effect."
When contacted by The Straits Times, Ogilvy replied with the contents of the memo.
Attempts to reach Mr Tham on his United States number were greeted by an automated voice message saying that his phone was not accepting calls.
Mr Tham, in his 60s and married, joined the ad giant in 1999. He was also co-chairman of Ogilvy's board.
In 2009, he became the first Asian to be named worldwide chief creative officer.
As the company's creative spokesman, he was a prominent player in the industry who spoke frequently at advertising conferences around the world.
At Ogilvy, he played a role in shaping the identities of brands such as Coca-Cola, IBM, Unilever and Louis Vuitton. He also led Ogilvy to win the prestigious Cannes Lions Network of the Year award five years in a row from 2012.
Mr Tham, in his 60s and married, joined the ad giant in 1999. He was also co-chairman of Ogilvy's board. In 2009, he became the first Asian to be named worldwide chief creative officer.
He was also one of four recipients of the Designer of the Year award at the 2009 President's Design Award in Singapore.
Under his leadership, the Ogilvy and Mather Asia-Pacific network received Campaign Brief Asia's Creative Network of the Year award between 2001 and 2008. He was awarded Creative Director of the Year in the same years, which led to his 2008 induction into the Campaign Brief Hall of Fame.
Ogilvy's former worldwide creative director Tuan Ching, who worked with Mr Tham for about nine years before leaving the company last year, told The Straits Times yesterday that he was shocked by the news of Mr Tham's termination.
"In my experience working with him, he was always very professional and kind to me," he said. "I was told the news only this morning, and I haven't had the chance to speak to him yet."
Mr Tuan added that Mr Tham strived for high standards and expected only the best from the team.
"As a friend, he was very generous and kind," he said.
Public relations veteran Rose Tan was shocked to hear the news, and said that in her interactions with Mr Tham, she has had only the best impressions of him.
Ogilvy is a subsidiary of London-based WPP, said to be the world's largest advertising and PR group. It was founded by David Ogilvy in 1948, and now boasts 132 offices in 83 countries, according to its profile on WPP's website.
In the memo, Mr Seifert called Mr Tham's termination "an important moment to reaffirm that no individual in this company is too senior or too important not to be held accountable for their actions". He also thanked staff for their support.
The Economic Development Board (EDB) used to feature Mr Tham on its website to showcase the best of Singapore's creative talent, but yesterday the profile was not there. EDB's public affairs director Praveen Randhawa said: "We have temporarily taken down Mr Tham's profile from our website until we have more information about what happened."
• Additional reporting by Jose Hong and Melody Zaccheus