A dealer dubbed the "Ketamine Queen" has agreed to plead guilty to supplying the drugs that killed "Friends" actor Matthew Perry, the US Department of Justice said on Monday.

Jasveen Sangha, 42, will admit several charges, including one of distribution of ketamine resulting in death or serious bodily injury in relation to the late star.

A dual citizen of the United States and Britain, she is expected to formally enter her pleas in the coming weeks She has been in federal custody since August 2024.

Sangha will become the fifth person to admit playing a part in the death of the actor, who had openly struggled for decades with substance addiction.

Perry, 54, was found dead in the hot tub of his Los Angeles home in October 2023. A criminal investigation was launched soon after an autopsy discovered he had high levels of ketamine – an anesthetic – in his system.

Last month, Dr Salvador Plasencia pleaded guilty to four counts of distribution of ketamine in the weeks before Perry's death. Another doctor, Mark Chavez, admitted last year to conspiring to distribute ketamine to Perry.

Plasencia allegedly bought ketamine off Chavez and sold it to the American-Canadian actor at hugely inflated prices.

"I wonder how much this moron will pay," Plasencia wrote in one text message.

According to her plea agreement, Sangha worked with a middleman, Erik Fleming, to sell 51 vials of ketamine to Perry's live-in personal assistant, Kenneth Iwamasa.

Iwamasa repeatedly injected Perry with the ketamine that Sangha supplied, including on October 28, 2023, when he administered at least three shots of Sangha's ketamine, which killed the actor.

The Justice Department said when Sangha heard news reports about Perry's sudden death, she tried to cover her tracks.

"Delete all our messages," she instructed Fleming.

When investigators raided Sangha's home they found methamphetamine, ketamine, ecstasy, cocaine, and counterfeit Xanax pills, as well as a money counting machine, a scale, and devices to detect wireless signals and hidden cameras, according to the Justice Department.

Sangha is expected to plead guilty to one count of maintaining a drug-involved premises, three counts of distribution of ketamine, and one count of distribution of ketamine resulting in death or serious bodily injury.

"She's taking responsibility for her actions," her lawyer Mark Geragos told AFP.

Sangha could face decades in prison when sentenced. (AFP)