Amir Mirzaei Hekmati, 28, who was sentenced to be hanged in January on a charge of spying for the CIA, could face execution immediately after an appeals court has reviewed his sentence. (Reuters TV/Reuters)

A former U.S. Marine sentenced to death in Iran for allegedly spying for the CIA could be saved if the Obama administration would consider a prisoner swap, his Iranian attorney said Wednesday.

Amir Mirzaei Hekmati, 28, who was sentenced in January to be hanged, could face execution immediately after an appeals court has reviewed his sentence, said lawyer Mohammad Hossein Aghassi. The court’s decision was expected Jan. 25; the reason for the delay is unclear, he said.

Aghassi stressed that it was essential for the Obama administration to do anything within its means to reach out to Iran — including offering a possible prisoner exchange — to save Hekmati, a U.S. citizen of Iranian descent.

Iran has repeatedly asked for the release of Shahrzad Mir Golikhani, an Iranian American sentenced for involvement in an attempt to export night-vision equipment to Iran, who is imprisoned in Florida. In total,Iran has a list of 11 people in U.S. captivity it says are illegally detained.

“His mother says Hekmati is in bad shape,” said Aghassi, whom Hekmati’s family asked Wednesday to represent their son.

U.S. officials confirmed that U.S. diplomats have had no access to Hekmati in prison, either directly or through the Swiss Embassy in Tehran, which represents U.S. interests there. A State Department official, speaking on the condition of anonymity to discuss the diplomatically sensitive case, said Iranian authorities do not recognize Hekmati’s dual citizenship.

“The Iranians claim that he is an Iranian citizen and thus there is no access requirement,” the official said. He added that the Obama administration is continuing to press Iran to release Hekmati, but he offered no details.

“We remain very concerned about the welfare of Mr. Hekmati,” he said.

U.S. officials have denied that Hekmati is a spy.

The United States has never officially reacted to Iranian suggestions of prisoner swaps, but Iran has in the past released Europeans in moves closely followed by the release of Iranians or high-profile visits to Iran by European diplomats. Iran has also unilaterally released dual nationals in the past, often after media pressure or interventions by religious leaders.

Hekmati’s case is made more sensitive by the fact that it coincides with a string of mysterious explosions and assassinations in Iran, which many here say are the work of a covert U.S. or Israeli sabotage program.

Precisely when and where Hekmati was arrested is unclear. Iranian news reports have said Hekmati was detained in late August or early September upon arrival in the country. His family members, who live in Michigan, have reportedly said he was in Iran to visit his grandmothers.

The former Marine appeared on Iranian state television in December and purportedly confessed to working for the CIA and being sent to Iran to act as a counterintelligence agent.

Hekmati’s mother traveled to Iran two weeks ago and has since met him three times in the visitors’ section of Evin prison, the last time Wednesday. Hekmati is being held in solitary confinement in a ward that is under the control of the Islamic republic’s intelligence service.

Hekmati’s mother, who declined to be interviewed out of fear of not being able to leave the country, told Aghassi that her son looked “unbelievably thin, feeble and depressed.” Aghassi said he has not been allowed to meet with his client, who until Wednesday was defended by a state-appointed lawyer.

“He is telling her, ‘Don’t worry about me, Mom,’ because he fears for her safety. He kept on repeating this line, his mother told me,” said Aghassi, a well-known lawyer in Iran who has won several prominent cases.

Hekmati told his mother that his two interrogators were sitting next to him when he appeared on Iranian television. “How could he do anything else than admit crimes under such circumstances?” Aghassi asked.

Aghassi said he hoped that the case, which he said was being reviewed by Iran’s highest judicial council, would be referred back to a lower court, which usually means a reduction in the initial sentence.

Hekmati’s case is very different from that of three Americans known as “the hikers,” who were held in Iran for more than two years, the lawyer said. Shane Bauer, Sarah Shourd and Josh Fattal held American nationality, while Hekmati, born in Arizona, traveled to Iran using his Iranian passport.

As Iran does not recognize dual nationality, the United States’ protecting power in Iran, Switzerland, will not be able to intervene. Additionally, mediation by the Persian Gulf state of Oman, which led to the release of the hikers, would be complicated.Bauer and Fattal were released in September 2011, Shourd in 2010. Aghassi said his client needed direct action from the U.S. government. In 2011, an Iranian Dutch woman was hanged almost immediately after losing her appeal, taking the Dutch Foreign Ministry and the European Union by surprise.

“This is something only the Obama administration can solve,” Aghassi said. “We can only pray that we will be successful in rescuing Hekmati.”

Staff writer Joby Warrick in Washington contributed to this report.