The wife of jailed Iranian-American pastor of Saeed Abedini urged US lawmakers on Wednesday not to green-light the landmark nuclear accord with Iran until her husband and other imprisoned Americans are released by the Iranian government.

Abedini, 35, a naturalised US citizen, is one of three American citizens known to be currently imprisoned in Iran.

The pastor's spouse, Naghmeh Abedini, said she was not very knowledgeable in nuclear matters to evaluate the accord but said there could have been parallel talks for the freedom of her husband and other US prisoners.

"It's very difficult for my children. And it's heartbreaking for me to see them growing up without their dad," Naghmeh said.

In 2013, Abedini was sentenced by an Iranian court to suffer eight years in jail for allegedly compromising Iran's national security by building home-based Christian churches in his native country.

He has been threatened by Islamic militants who are also in the same prison west of Tehran, according to his wife.

The pastor's physical and psychological health has worsened because of lack of medical attention as well as his solitary confinement.

Naghmeh said the prisoners' freedom should have been guaranteed before Obama even agreed to the nuclear negotiations, which has resulted in an accord that would allegedly limit Tehran's nuclear programme in return for the lifting of economic sanctions crippling Iran's economy.

Obama met Abedini's wife and their children when he visited them in Boise earlier this year.

Naghmeh said she is now placing her hopes on her husband's release on the US Congress, adding that she has heard some Republicans and even Democrats saying they would only approve Obama's nuclear deal with Iran on the condition that Iran would free all its American detainees.