British MPs have called for an investigation following the death of a whistleblower who had raised serious allegations linked to BGC Partners, the financial brokerage firm whose chief executive Howard Lutnick has been publicly associated with Jeffrey Epstein.

The whistleblower, identified as Andriesz, had accused the Financial Conduct Authority (FCA) of failing to act on allegations he first brought to the regulator as far back as 2018.

In July, Andriesz told MPs and campaigners that the FCA had been fully informed about the serious allegations he had raised and accused the regulator of inaction.

The FCA responded at the time, stating it had acted on his allegations and pointing to a supervision order it had issued based on his information.

Andriesz, however, rejected that characterisation. In his view, the supervision order amounted to little more than a regulatory "slap on the wrist" and had made it harder for him to pursue a whistleblower retaliation claim against BGC at tribunal.

Later that month, he addressed a meeting of the campaign group the Transparency Task Force, where he said the FCA was not fulfilling its obligations to the public or to whistleblowers and merely "pays lip service" to the rules and regulations.

"It protects the institution and then exposes the whistleblower to extreme retaliation and devastation to their lives and families," he said.

Following his death, the FCA announced it was appointing a new non-executive director to its board, former Bank of England director Lea Paterson, to conduct a review into Andriesz's treatment and the regulator's handling of his whistleblower allegations.

An FCA spokesperson said: "We are very sorry to hear of Mr Andriesz's death. Our thoughts are with his family and friends."

The spokesperson added: "Since expressing our condolences, we'd asked Lea Paterson, who has just joined our board as a non-executive director, to review how we interacted with Mr Andriesz to learn any lessons for the future."