LONDON — Andrew Mountbatten-Windsor — formerly known as Prince Andrew and the younger brother of King Charles III — was arrested on Thursday on suspicion of misconduct in public office, ABC News understands.

In a statement, Thames Valley Police said they had “arrested a man in his sixties from Norfolk on suspicion of misconduct in public office and are carrying out searches at addresses in Berkshire and Norfolk.”

“The man remains in police custody at this time. We will not be naming the arrested man, as per national guidance,” the statement said.

Photos from Wood Farm on the Sandringham estate in eastern England showed what appeared to be police officers arriving in several unmarked vehicles. Thursday marks Andrew’s 66th birthday.

In a statement issued on Thursday, Charles said, “I have learned with the deepest concern the news about Andrew Mountbatten-Windsor and suspicion of misconduct in public office.”

“What now follows is the full, fair and proper process by which this issue is investigated in the appropriate manner and by the appropriate authorities. In this, as I have said before, they have our full and wholehearted support and co-operation,” Charles added.

“Let me state clearly: the law must take its course. As this process continues, it would not be right for me to comment further on this matter. Meanwhile, my family and I will continue in our duty and service to you all.”

Andrew’s arrest on Thursday follows the emergence of documents detailing communication between Andrew and the late convicted sex offender Jeffrey Epstein.

Several emails released by the U.S. Justice Department showed Epstein’s correspondence with a Andrew’s aide David Stern and suggest the royal may have planned to use his role as a special U.K. representative for trade and investment to further his own business interests.

The emails in question date back to 2010. Andrew served as a British trade envoy from 2001 until 2011, when Buckingham Palace announced that he would give up the role following criticism over his friendship with controversial figures, including Epstein.

Andrew has previously denied wrongdoing with respect to Epstein.

Thames Valley Police told ABC News last week that they were assessing reports of Andrew’s alleged misconduct in office as trade envoy.

“We can confirm receipt of this report and are assessing the information in line with our established procedures,” a Thames Valley Police spokesperson said in a statement on Feb. 9.

This is a developing story. Please check back for updates.

ABC News’ Zoe Magee, Angeline Jane Bernabe, James Hill and Melanie Schmitz contributed to this report.