Martin Sorrell has "strenuously" denied fresh allegations he used WPP money to pay sex workers and created a "toxic environment" within the holding group.
The new allegations have been linked to the mogul's departure from WPP earlier this year.
The Financial Times is reporting former staff claims that he had bullied junior employees and was spotted entering an address in a London red-light district.
Sorrell's spokesperson issued a statement on Sunday, saying: “Sir Martin signed a non-disclosure agreement when he stepped down which precludes him from discussing any of the circumstances surrounding his departure. He has rigidly adhered to this obligation and will continue to do so.
“As regards the allegations [that company funds were paid to a sex worker], Sir Martin strenuously denies them. He will be making no further comment at this time.”
Martin left WPP, the company he founded more than 30 years ago, in April this year following allegations of personal misconduct. WPP carried out an inquiry into allegations that he misused company funds, but the details of the investigation were never disclosed.
A spokesman for WPP issued a statement, saying: "We are not able to comment on individual cases or specific allegations, but everyone at WPP should feel able to raise concerns and to have them listened to and acted upon as appropriate.
"The board takes this matter very seriously, and has tasked the new management team with reviewing how our policies are implemented in practice and where and how we need to make improvements going forward."
Sorrell, who didn’t have a non-compete clause in his contract, is planning to create a new advertising venture and is set to speak at Cannes Lions next week.
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