WPP’s long-time chief executive Sir Martin Sorrell is currently being investigated by the company for alleged misuse of assets and improper personal conduct.

Information surrounding the allegations remain scarce, but the advertising giant’s board has brought in an independent counsel to carry out an investigation into the accusations, according to the Wall Street Journal.

According to the company, the allegations levelled against Sorrell are not financially material to WPP.

Of the allegations, Sorrell said: “Reports in the media have stated that WPP is investigating an allegation of financial impropriety by me, specifically as to the use of company funds.

“This allegation is being investigated by a law firm. I reject the allegation unreservedly but recognise that the company has to investigate it.”

“I understand that this process will be completed shortly.”

Sorrell has been at the helm of WPP since 1986, following a private investment in wire shipping basket company Wire & Plastic Products the year prior. From here, he built the advertising empire that now boasts 3,000 offices in 112 countries.

Following news of the allegations, shares in WPP fell by over three per cent. Although, the downward trend of shares in WPP has been ongoing for the last year or so.