An Iranian-American dual national held in Tehran was granted a brief leave from prison over health concerns, his Washington-based lawyer said Sunday.

Lawyer Jared Genser said in a statement that his 81-year-old client would be out of Tehran's Evin prison on a four-day leave. Namazi has undergone surgery already while imprisoned to have a pacemaker installed.

Genser says his client's leave should be made permanent given his poor health.

Iranian state media did not immediately report Namazi being granted leave.

U.S. State Department spokeswoman Heather Nauert said: "We welcome the release of Baquer Namazi given his deteriorating health but we note that his release is only temporary. We call for the immediate and full release of the Namazi family, including his son Siamek, as well as other Americans unjustly held by the Iranian government"

Baquer and Siamak Namazi are among several dual nationals held by Iran. Both Namazis are serving 10-year prison sentences after closed-door trials.

Analysts believe Iran is holding them as bargaining chips for future negotiations with the West.