THE HAGUE (Reuters) - U.S. Secretary of State Hillary Clinton said Tuesday an American diplomat had met Iran's delegate at an international conference in the Hague -- a sign of tentatively improving ties after decades of hostility between Washington and Tehran.
The United States directly gave a letter to Tehran over the case of three Americans, Clinton said.
Iran however played down the encounter, saying no meeting had taken place.
Clinton said the U.S. special envoy to Afghanistan and Pakistan, Richard Holbrooke, met briefly with Iranian deputy foreign minister Mohammad Mehdi Akhoundzadeh on the sidelines of the Hague conference.
"It did not focus on anything substantive. It was cordial, it was unplanned and they agreed to stay in touch," Clinton said.
Iran's official IRNA news agency quoted Akhoundzadeh as denying a meeting had taken place.
"We would have informed our nation if we had talks with the the Americans over Afghanistan in The Hague, like what we did about talks over Iraq with America," he said.
"You can be sure that if Iran wants to hold talks with America, everyone can be informed about it and there is nothing to hide."
Asked about the IRNA report, a senior U.S. official reaffirmed the two men had exchange pleasantries and a brief cordial meeting had taken place.
Whatever the precise nature of the encounter, it reflected a strong wish by the Obama administration to engage Iran on issues such as Afghanistan and help kickstart what the new U.S. president says could be a "new beginning" with Tehran.
Former U.S. President George W. Bush branded Iran as part of an "axis of evil" along with North Korea and Saddam Hussein's Iraq because of its support for anti-Israeli militant groups.
The two countries are currently at odds over Iran's nuclear program, which the West says is a cover to build an atomic bomb and Iran says is for peaceful energy use.
The United States cut off diplomatic ties with Tehran during the 1979-1981 hostage crisis in which militant Iranian students held 52 diplomats hostage at the U.S. embassy for 444 days.
Clinton said a letter was handed directly to the Iranian delegation at the conference.
Usually such diplomatic exchanges are made via the Swiss, which represent U.S. interests with Iran because of the lack of diplomatic ties.
The letter asked for "humanitarian help" for three Americans she said were unable to return to the United States.
They are Robert Levinson, a former FBI agent who went missing two years ago while on a business trip to Iran, and a freelance journalist, Iranian-American Roxana Saberi. The third, Esha Momeni, is an Iranian-American student.
"We ask Iran to use all its facilities to determine the whereabouts and ensure the quick and safe return of Robert Levinson, and grant the release of Roxana Saberi, and permission to travel for Roxana Saberi and Esha Momeni," said an excerpt of the letter released by the U.S. State Department.
Clinton indicated a positive response would help relations with Iran after three decades of enmity.
"These acts would certainly constitute a humanitarian gesture by the Islamic Republic of Iran in keeping with the spirit of renewal and generosity that marks the Persian new year," she told a news conference.
Earlier at the meeting, Iran's delegate agreed to help fight drugs trafficking in Afghanistan but also criticized the presence of foreign troops in Afghanistan.
"The presence of foreign forces has not improved things in the country and it seems that an increase in the number of foreign forces will prove ineffective too," Akhoundzadeh said.
Clinton welcomed Iran's pledge to fight drugs trafficking and Iran put forward "some very clear ideas that we will be pursuing together."
She said she had no direct dealings with Akhoundzadeh. They were seated alphabetically at a horseshoe-shaped table in the meeting room when they made their speeches.
Reporting by Sue Pleming; editing by Angus MacSwan