(Reuters) -WiseTech Global said on Monday it was reviewing a "full range of matters" concerning its CEO after media reports made allegations about his personal life including payments to a past sexual partner, sending its shares slumping 18%.

The Australian Financial Review and other media outlets reported that a woman who had a sexual relationship with Richard White made a raft of claims against the billionaire chief executive and WiseTech Global founder in late 2020, including allegations he had engaged in inappropriate behaviour.

White could not immediately be reached for a comment while WiseTech Global declined to comment further.

Shares of the Australian technology firm dived as much as 18.3% to A$100 and were on track for their worst trading session since late August, 2023. Shares were last down 12.8%.

"The negative headlines and uncertainty as to how this story may unfold took a toll on WiseTech's shares today," said Tim Waterer, market analyst at KCM Trade.

"Investors are left with questions over how this scandal may impact the founder's role in the company moving forward."

The Australian Financial Review report said White, 69, had approached numerous female entrepreneurs through text messages and social media with offers of professional support that could shift into crude or suggestive language.

Shares in Wisetech Global have fallen over 11% since the start of October when reports about White's personal life started emerging.

White has also continued to sell down his stake in the tech company. In the latest sell-off, White sold 351,038 shares at an average price of A$131.22 apiece between Oct. 11 and Oct. 17, according to a notice filed on Friday.

(Reporting by Rishav Chatterjee in Bengaluru; Editing by Sandra Maler and Lincoln Feast.)