Prince William and Kate Middleton are losing a major member of their staff.

The Duke and Duchess of Cambridge announced on Thursday that Jason Knauf, who has worked for the couple since 2015, will be stepping down as the Chief Executive of their Royal Foundation at the end of December 2021.

"Jason has been an integral part of our team since 2015. We are immensely grateful for his hard work and commitment, both at The Royal Foundation and previously as our Communications Secretary," the couple's statement to Hello! began

"Since taking over as Chief Executive, Jason has driven positive change, making our vision for our charitable work and the causes that matter most to us a reality. We are sad to see him go but wish him all the very best in his future career," it continued. 

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"We look forward to launching the recruitment search shortly and welcoming a new Chief Executive later on this year," the pair concluded. 

Prince William (left) and Kate Middleton (right) have lost a senior member of their staff.  (Getty Images)

Meanwhile, Knauf said in his own statement it has been "the privilege of my career" working for the British royals

"I will always be grateful for the opportunity I have had to support their leadership in the UK and internationally," he added.

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Knauf previously worked at the Royal Bank of Scotland before joining William and Middleton's household as a communications secretary then became a senior adviser before starting as chief executive in 2019. 

He also worked for Prince Harry and Meghan Markle as a communications secretary. 

The Texas native made headlines in early March when it was reported he filed a complaint in October 2018 accusing Markle of allegedly bullying staffers

Jason Knauf, Chief Executive of Kate and William's Royal Foundation, is leaving in December 2021.  (Max Mumby/Indigo/Getty Images)

The complaint alleged that the former American actress drove two personal assistants out of the household and undermined the confidence of a third staff member.

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The Times in the U.K. reported Knauf allegedly sent an email to Simon Case, who served as William’s private secretary at the time. The email was then forwarded to Samantha Carruthers, head of human resources. In the email, Knauf claimed Carruthers "agreed with me on all counts that the situation was very serious," adding, "I remain concerned that nothing will be done."

A spokesperson for the Sussexes fired back at the allegations reported by The Times.

"Let’s just call this what it is – a calculated smear campaign based on misleading and harmful misinformation," the spokesperson told the outlet.

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"We are disappointed to see this defamatory portrayal of The Duchess of Sussex given credibility by a media outlet," the spokesperson continued.

Fox News' Stephanie Nolasco contributed to this report.