Israeli authorities say that many of the released prisoners had resumed terrorism activity, either by joining Hamas or recruiting members to terror cells
A source close to the Taliban said the group was willing to move forward so long as most of the 5,000 prisoners demanded were released.
An Iranian-American doctor has returned to Iran, Iranian state media reported on Monday.
The US official reiterated an appeal for Iran to release American citizens Baquer Namazi, his son Siamak Namazi and conservationist Morad Tahbaz.
Michael White had been released from an Iranian prison in mid-March on medical furlough but was held in Iran under Swiss custody.
"Hamas will not be quiet about prisoners sitting in Israeli prisons; some of them for over 40 years already."
'It seems that there is now a real possibility for a deal between Hamas and Israel for the release of all the prisoners of war and those missing in action'
'To miss the opportunity now, would be a national irresponsibility'
Iran's reported temporary release of 100,000 prisoners since February - including prisoners of conscience and dual and foreign nationals - was welcomed by the United Nations on Friday as a good step.
A German mediator who was involved in the release of IDF soldier Gilad Shalit in 2011 is participating in the current talks.