Thomas Markle, the estranged father of Prince Harry's wife, Meghan Markle, was arrested in Florida on Friday over alleged possession of images of child sexual abuse, officials said.
Markle, 82, is charged with one count of "possession of child pornography" and is to make an initial court appearance in Tampa on Friday, US Attorney Bill Essayli said in a statement.
"Mr Markle is accused of possessing child sexual abuse material, including photographs depicting himself with minor girls," Essayli said. "These allegations are extremely serious, and we will prosecute Mr Markle to the fullest extent of federal law."
Markle was taken into custody by FBI agents early Friday at the retirement home where he lives in Lakeland, Florida.
The Justice Department said Markle allegedly "kept child sexual abuse material (CSAM), including sexually explicit photographs of himself with prepubescent girls, in two Los Angeles-area storage units he rented for nearly two decades."
"Inside the units, agents seized approximately 78 items, including slides, film negatives, and books that contained suspected CSAM," it said.
Markle could face up to 20 years in prison if convicted of possession of child sex abuse material.
Pictures of child sex abuse have also allegedly been found at Markle's former home in the Philippines and at a storage unit he rented in Mexico.
The British tabloid The Sun reported last month that Markle's son, Thomas Markle Jr, had discovered the child sex abuse images while going through boxes found in his father's former home in the Philippines.
Markle had been living in Cebu in the Philippines until reportedly returning to the United States earlier this year.
Meghan Markle said last month that she was "deeply distressed" by accusations that her father possessed images of child sexual abuse.
She said she had blocked contact between him and her children over previous "troubling and disturbing" allegations.
Harry, the second son of King Charles III and estranged brother of heir to the throne Prince William, married Meghan, an American former actress, at Windsor Castle in May 2018.
The couple left Britain and quit royal duties in 2020 but made an unexpected return with their two children to live in the United Kingdom in August.