Iranian Foreign Ministry Spokesman Ramin Mehmanparast says Tehran is holding the US responsible for the June 2009 abduction of an Iranian national, Press TV reported.
Pointing to Washington's continued silence on the matter, Mehmanparast told Press TV on Sunday that Iran would spare no effort to support Shahram Amiri and other Iranian nationals in foreign custody.
"After releasing Mr. Shahram Amiri's tape, the US State Department spokesman said Washington had received the documents handed over to the Swiss Embassy in Tehran by Iran," Mehmanparast said.
"The spokesman said Washington would review the issue and respond. We are still waiting for an answer from the State Department. They should be held responsible for the Iranian national and his safe return to Iran," he added.
Since last June, two video and one audio message featuring the Iranian scholar, who went missing while on a pilgrimage in Saudi Arabia, have emerged.
"I was abducted on the 13th of Khordad 1388 (June 3, 2009) in a joint operation by terror and kidnap teams from the US intelligence service CIA and Saudi Arabia's Istikhbarat. I was kidnapped from the holy city of Medina," Amiri says in the first message released on Monday, June 7.
In the second video, Amiri contradicted his earlier statements, saying that he was in the United States of his own free will to further his education. He also dismissed all rumors about his defection.
However, in the latest audio message obtained by the Iran's intelligence sources, Amiri insists that he was offered 10 million dollars to appear on CNN and announce that he had defected to the US willingly.