DA Washington-based lawyer for an Iranian-American dual national held in Tehran says his 81-year-old client has been granted a brief leave from prison over health concerns.

Lawyer Jared Genser said in a statement Sunday that Baquer Namazi 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.

Namazi and his son, Siamak, 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.

U.S. State Department spokeswoman Heather Nauert welcomed the temporary release, but called for Namazi's "immediate and full release" as well as that of his son and all other Americans currently held in Iranian jails.

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.

— Heather Nauert (@statedeptspox) January 28, 2018