Pastor Saeed Abedini has been severely beaten in Iran while being transferred from the hospital, which he spent the last two months in, back to Rajai Shahr prison, the American Center for Law and Justice reported.
"This is an extremely disappointing development - one that breaks my heart," said Abedini's wife, Naghmeh. "Our family is deeply saddened and we continue to pray for Saeed - for his safety and his release. We are very grateful that so many people around the world continue to pray for Saeed."
The ACLJ, which represents Naghmeh and the couples' two children in the U.S., reported on Tuesday that the transfer occurred without any advance notice. Abedini's family members in Iran added that he was "severely beaten" during the incident, though the precise nature of his injuries was not described.
The pastor, who turned 34-years-old on May 7, had been recovering at the Iranian hospital for the past couple of months, being treated for injuries he sustained in previous beatings.
The U.S. citizen, who was arrested in July 2012 while working on an orphanage project, is serving eight years in prison for his Christian faith, the ACLJ says.
He has gone through a tumultuous experience in Iran since his arrest, first being held at the notorious Evin prison where he received many of the beatings, before being transferred to Rajai Shahr prison last year. When he was initially sent to the hospital in March, he was shackled by guards who lashed out violently against him, while his family there were prevented from seeing him.
Abedini's treatment reportedly improved, however, and he was allowed visitations and was was provided with nutritional meals, before the latest beating where he was sent back to Rajai Shahr.
One of Abedini's family members has said that an Iranian guard mentioned Iranian nuclear talks as a possible motive for the transfer.
The ACLJ and other campaigners for Abedini's freedom have pointed out that the U.S. government should ask for the pastor's freedom in any talks related to loosening international sanctions on Iran over its nuclear program - something which the U.S. failed to do in late 2013 negotiations, where an Iranian nuclear scientist was released as part of a deal instead.
The global campaign calling for the freedom of pastor Abedini continues, with an ACLJ petition on the issue, collected over 257,000 signatures to date.