US congressional aides are to visit Iran next month in a bid to improve relations, an American senator says.
US aid workers helped in Bam's relief effort
Senator Arlen Specter said the trip was arranged during a meeting with Iran's ambassador the UN on Wednesday.
He said Iran was "skittish" about formal government-to-government talks but would accept a staff delegation.
If the visit goes ahead it is thought to be the first by US officials since Washington and Tehran severed ties after the 1979 Iranian revolution.
Mr Specter, a Pennsylvania Republican, and Ohio Republican Representative Bob Ney organised the informal dinner with Iran's UN ambassador Mohammad Javad Zarif.
Mr Zarif's appearance in Washington was significant as he needs special clearance to move outside New York, where the United Nations headquarters are based.
'Setting the stage'
The talks were described as civil and fruitful.
Mr Specter said the US delegation was confirmed and would be going in February, although he gave no date.
"They [the Iranian government] are skittish about going too far and we have gotten to the point where they will accept a small delegation of staffers," he said.
"I think that will set the stage for meetings with parliamentarians and I think we are laying the groundwork for trying to improve relations with Iraq, which would be a big boost".
Mr Ney was also hopeful, although he said February's trip was "not set in stone".
"I hope it happens, and from what Ambassador Zarif said, he hopes it happens. I don't have any confirmation that the trip will happen".
The US State Department suggested it would have no objections to such a trip.
"It would be fine with us if they decided to go," said spokesman Richard Boucher.
Two years ago that President George Bush included Iran in his "axis of evil" along with Iraq and North Korea.
But more recently there have been signs of a thawing of relations.
The US provided relief assistance to the Iranian city of Bam following its devastating earthquake in December.
However, its proposal to send a high-level humanitarian delegation was rejected by Tehran.