The mothers of three Americans jailed in Iran for 10 months were expected to arrive back in the U.S. after visiting their children in Tehran but failing to secure their release.

The Swiss ambassador in Iran told AP Television News there were no negotiations with Iranian officials to free their children. Washington and Tehran broke off diplomatic relations following the 1979 Islamic Revolution, and Switzerland handles U.S. interests in Iran.

"The point was that they should see their children. They have seen them quite a lot over the last two days," Ambassador Livia Leu Agosti said late Friday in an interview at the Tehran airport after the mothers left the country. "It was a visit to the children. That was the purpose."

Also, Iran announced Friday that two of its nationals held in Iraq by U.S. forces for years had been freed, raising the possibility that a behind-the-scenes swap was in the offing or that their release was a gesture of goodwill in an attempt to free the Americans.

The Iranians' release "may have some diplomatic effect on this case," the Americans' lawyer, Masoud Shafii, told the AP.

The U.S. has said it is not offering a direct swap, and Iranian officials made no public connection between the freed Iranians and the Americans.

The Americans -- Sarah Shourd, 31; her boyfriend, Shane Bauer, 27; and their friend Josh Fattal, 27 -- have been held in Iran since July, when they were arrested along the Iraqi border. Iran has accused them of espionage; their families say that the three were hiking in Iraq's largely peaceful mountainous northern Kurdish region and that if they crossed the border, it was accidental.

The mothers -- Nora Shourd, of Oakland, California; Cindy Hickey, of Pine City, Minnesota; and Laura Fattal, of suburban Philadelphia -- had hoped to at least make a face-to-face appeal for their children's release to Iranian leaders. They were expected to arrive Saturday afternoon in New York on a flight from Dubai, a spokeswoman said Friday.

Asked whether there were any positive signs from Iranian authorities, Agosti told APTN: "Well, they were very generous in the time that they allotted the mothers to be with their children. So it was a good gesture."

Their detention has become entangled in the confrontation between the United States and Iran. Iranian leaders have repeatedly suggested a link between their jailing and that of a number of Iranians by the United States whose release Tehran demands. Further increasing tensions, the U.S. announced before the mothers' arrival in Tehran that it had support from other major powers for a new set of U.N. sanctions against Iran over its refusal to stop uranium enrichment.

Iran has said it allowed the mothers to visit the Americans as a humanitarian gesture, and state TV gave heavy coverage to the mother's first reunion with their children Thursday at the high-rise Estaghlal hotel near Evin prison, where the Americans were being held. They embraced, kissed and cried, then sat for a lavish meal in the hotel restaurant. It was the first public look at the three young Americans since their detention.

Josh Fattal told reporters, "We hope we're going home soon, maybe with our mothers."

They appeared healthy, wearing jeans and polo-style shirts. Sarah Shourd wore a maroon head scarf. They described their routines behind bars and being allowed books, letters from home, the ability to exercise and the one hour each day they are all together.

The three Americans were taken back to Evin after the meeting, witnesses at the hotel told AP.

They are all graduates of the University of California at Berkeley. The last direct contact with their families had been a five-minute phone call in March.

Iran has hinted in the past that it wants to swap the three Americans for a number Iranians being held by the United States -- including several who have been tried and convicted in the United States over violations of American sanctions on Iran. Also among them is a nuclear scientist, Shahram Amiri, who disappeared during a visit last year to Saudi Arabia, raising speculation he defected to the West.