The United States Wednesday dismissed Iranian claims that it has uncovered new evidence against two jailed U.S. citizens accused of anti-state activity. The State Department says charges against the two Iranian-Americans have no basis in fact. VOA's David Gollust reports from the State Department.

The State Department has renewed its call on Iran to release its American detainees amid a claim from Tehran that it has unearthed new evidence against two of them - Haleh Esfandiari and Kian Tajbakhsh.

An Iranian judicial spokesman made the announcement Tuesday and said fresh investigations have begun based on that information.

Esfandiari, director of the Middle East program at Washington's Woodrow Wilson International Center for Scholars, has been held in solitary confinement in Tehran's Evin Prison since her arrest in early May.

Tajbakhsh is a New York-based urban planning consultant with the Open Society Institute of philanthropist George Soros and has also been jailed since May.

Both are being held on unspecified security charges, and Tuesday's announcement dashed hopes for their early release.

In a talk with reporters, State Department Spokesman Sean McCormack said the alleged new evidence is no more credible than what he said were baseless previous charges, and he said there is no reason why the Americans should still be detained.

"These are people and especially in the case of Mrs. Esfandiari, people who have sought to build bridges between the Iranian people and the American people and the outside world," said McCormack.

"There's no reason why they should not be allowed to leave. I can't explain to you the motivation of the Iranian government in not allowing these people to leave. But the fact of the matter is they should be allowed to return home and be reunited with their families," he continued.

Former U.S. Congressman Lee Hamilton, who heads the Wilson Center, said Tuesday there is no shred of truth to the allegations against the 67-year-old Esfandiari, and that the organization is "gravely concerned" about her physical and mental state.

At least two other Iranian-Americans are facing similar charges. They are Ali Shakeri, a board member of the University of California at Irvine's Center for Citizen Peacebuilding and Parnaz Azima, a journalist for the U.S.-funded radio Farda.

Shakeri is in jail while Azima has been barred from leaving Iran.

Spokesman McCormack said the United States is trying various channels to get information about the detention cases and also about retired U.S. FBI agent Robert Levinson, who disappeared after arriving in Iran earlier this year.