US Secretary of State John Kerry appealed to the Iranian government to release an ex-US marine who has spent nearly three years in prison on what what he termed “false espionage charges.”

In a statement released on Monday to mark Memorial Day in the US, Kerry raised the matter of Amir Hekmati, a dual US-Iranian citizen who was arrested in 2011 and convicted of working for the CIA.

“On this Memorial Day, we honor brave Americans who gave their lives for the notion that someone else’s freedom is connected to our own,” Kerry said. “But this Memorial Day also marks another milestone: 1,000 days since an American veteran, Amir Hekmati, was unjustly detained while he was visiting his family in Iran.”

“We respectfully request that the Government of the Islamic Republic of Iran release Mr. Hekmati so that he may be reunited with his family in the United States,” he asked.

“Mr. Hekmati has spent almost three years in an Iranian prison on false espionage charges,” Kerry noted. “We remain especially concerned about reports of Mr. Hekmati’s health in prison. Mr. Hekmati’s family in the United States has endured the hardship of his absence for too long. He is the eldest son, and his family misses him and needs him home.”

On Sunday an Iranian news agency reported that Hekmati, who was born in Arizona, had appealed for a new trial.

The report by the official ISNA news agency quoted Mahmoud Alizadeh Tabatabaei, a lawyer of Amir Hekmati, as saying the retrial request came over a possible mistake by the judge in the case and the “inconsistency” between his alleged crime and its punishment.

In April, an Iranian appeals court overturned Hekmati’s death sentence for espionage after he appealed.

Another court instead found him guilty of “cooperating with hostile governments.”

His family, now in Michigan, says Hekmati is innocent and only went to Iran to visit his grandparents.

AP contributed to this report.