Prince Harry's US immigration records should be unsealed in the light of revelations about drug-taking in his recent book, a conservative think tank will argue in a federal court next week.

The Heritage Foundation is suing the US government to find out if it acted according to procedure when it granted the Duke of Sussex a US visa. Under US immigration law, evidence of past drug use can be grounds to reject an application.

The case will be held in front of a federal judge on June 6 at the US District Court for the District of Columbia.

The Heritage Foundation filed a complaint under the Freedom of Information Act, attempting to compel the government to release Harry's immigration file. "The requested information is of immense public interest," reads an amended complaint filed on May 5.

"Widespread and continuous media coverage has surfaced the question of whether DHS [Department of Homeland Security] properly admitted the Duke of Sussex in light of the fact that he has publicly admitted to the essential elements of a number of drug offenses in both the United States and abroad," it continues.

The Heritage Foundation has long been one of the most influential conservative think tanks in Washington. Nile Gardiner, director of the foundation's Margaret Thatcher Center for Freedom, tweeted on Thursday that there was a public interest in disclosing Harry's records.

"Given his extensive drug use admissions, normally disqualifying for entry into the United States, the American people deserve answers to the serious questions raised by the evidence," he wrote in a Twitter post. "Did DHS in fact look the other way, play favorites, or fail to appropriately respond to any potential false statements by Prince Harry?"

CNN has asked a representative for Prince Harry for comment.

Harry most recently confessed to taking various recreational party drugs in his explosive memoir "Spare," which was published in January.

The Duke of Sussex admitted to having taken cocaine, smoked marijuana and tried magic mushrooms. Harry, who moved to California with Meghan in 2020, has opened up about his experiences with cocaine as a teenager.

"Of course. I had been doing cocaine around this time. At someone's country house, during a shooting weekend, I'd been offered a line, and I'd done a few more since," Harry revealed.

"It wasn't much fun, and it didn't make me particularly happy, as it seemed to make everyone around me, but it did make me feel different, and that was the main goal."

Harry described himself as a "deeply unhappy seventeen-year-old boy willing to try almost anything that would alter the status quo."

Elsewhere in the autobiography, the fifth in line to the throne discussed graduating from smoking tobacco to weed during his days at Eton College, as well as revealing that he tried magic mushrooms during a trip to the United States.

Harry said he briefly stayed at actor Courteney Cox's house where "we spotted a huge box of black diamond mushroom chocolates" and he and a friend ate several and "washed them down with tequila."

Prince Harry's autobiography was not the first time the royal had touched upon his recreational drug use when he was younger.

He previously spoke with Oprah Winfrey of how he abused drugs and alcohol in his late 20s and early 30s as a coping mechanism for the pressures of royal life.

"I was willing to drink, I was willing to take drugs," he said. "I was willing to try and do the things that made me feel less like I was feeling."