Iran's deputy foreign minister said on Wednesday that Iranian diplomats discussed the case of Americans still held captive by Tehran. The issue was raised on the sidelines of negotiations in Vienna earlier this month that led to the landmark deal on curbing Iran's nuclear program.

Earlier, Secretary of State John Kerry had said that U.S. officials raised the issue of captive Americans with Iran every day during the recent nuclear talks, but did not make it part of the negotiations because they feared it would scuttle any deal.

In the Iranian capital, Tehran, Deputy Foreign Minister Abbas Araghchi told reporters on Wednesday that cases of "imprisoned citizens" were discussed with their American counterparts during the nuclear talks.

He said "humanitarian" reasons had motivated the discussion but did not elaborate.

It was the first confirmation by the Iranians of any talks that may have involved the fate of former U.S. Marine Amir Hekmati, Christian pastor Saeed Abedini, Washington Post reporter Jason Rezaian, and retired FBI agent Robert Levinson.

Araghchi spoke on the first anniversary of Rezaian's arrest on espionage charges.