Officials at Nato HQ have opened dialogue with Iran for the first time in years
An Iranian diplomat has held informal talks with Nato officials for the first time in 30 years.
Senior Nato negotiator Martin Erdmann said he had met Iran's ambassador to the European Union, Ali-Asghar Khaji, more than two weeks ago.
"This is another good step in engaging Iran in the international community," said Mr Erdmann.
A Nato spokesman, James Appathurai, said the talks with Mr Khaji had concentrated on Afghanistan.
Iranian diplomats have confirmed their attendance at a US-backed talks on Afghanistan taking place at The Hague next week.
UN Secretary General Ban Ki-moon, as well as delegates from more than 80 countries, are due to attend the conference.
"The fact that Iran has decided to go," said Mr Appathurai, "is good news and constitutes a new step."
In Washington, a spokesman at the State Department, Gordon Duguid, also welcomed the Iranian decision to go to The Hague talks.
"The Iranians will be around the table," said Mr Duguid. "We will hear their points of view and they will hear our points of view about Afghanistan."
Some news reports have suggested that Nato countries with forces in Afghanistan might have an interest in using Iran as a supply route.
Correspondents also point out that the opening of a dialogue between Nato and Iran comes as President Barack Obama has set new priorities for the United States in Afghanistan and weeks after he signalled a willingness to revitalise American relations with Tehran.