Naghmeh Abedini, wife of imprisoned American pastor Saeed Abedini, described the increased persecution her husband has faced in recent days in a statement released through the ACLJ.

Saeed has been held captive in Iran for more than three years, and has recently been berated by prison guards who insist he must denounce Christ to be set free.

"They continually threaten Saeed that the only key to his freedom is denying Christ and returning to Islam," Naghmeh reported. "Saeed refuses to deny Christ and continues to be a light and witness in that dark prison.

"These threats, coupled with the fact that there have been mass executions during the last week in Rajayee Shahr prison, have really taken their toll on Saeed. He asks for prayer for continued strength," she said.

Pastor Abedini became a Christian in 2000, and maintains that he travelled to his native country in September 2012 to help build a state-run orphanage.

He was arrested for proselytising, and has reportedly been beaten by inmates and guards while incarcerated. He was sentenced to eight years in prison in January 2013.

"The guards have also been threatening Saeed that he will never go free and additional charges (and years) will be added to his sentence (which they have done to other Christians and fellow inmates)," Naghmeh added.

Naghmeh and her two children have been steadfast in their efforts to secure Saeed's freedom. Naghmeh has met with President Obama and other world leaders, in addition to providing media interviews and accounts of Saeed's treatment to garner public support for his release.

Secretary of State John Kerry expressed confidence that the White House will be able to negotiate a release in the next two and a half months as part of a nuclear program agreement with Iran.

Over 300,000 people have signed an ACLJ petition calling for Pastor Abedini's release. The human rights organisation also began a postcard campaign to flood the White House with requests for Abedini's freedom.