The talks in Bulgaria on Thursday come as Iran stands firm ahead of a Friday deadline set by the UN Security Council for Tehran to freeze uranium enrichment work as a "confidence-building measure."

Though NATO is not directly involved in the Iran crisis, the meeting will provide an obvious opportunity to take stock of the situation.

"I would guess a lot of them are thinking about what happens if this deadline passes without a change of heart from the Iranians," a senior NATO diplomat told the AFP news agency.

"NATO is concerned by the issue, but it is not playing a leading role," NATO Secretary General Jaap de Hoop Scheffer said.

Scheffer, who will be leading the NATO talks, already has enough on his plate with the official agenda for the informal Sofia meeting, including discussion of Darfur, as well as preparations for a NATO summit in the Latvian capital Riga in November.

NATO support for Darfur

The alliance has said it is ready to increase its logistical support for an African Union-led peacekeeping force in the violence-scarred Sudanese region, as well as for a UN force expected to replace it later in the year.

Intense discussions are underway between the governments of NATO's 26 member states over how exactly this can be done without actually sending combat troops into the region. United Nations Secretary General Kofi Annan requested NATO expand its support to the African Union.

"NATO stands ready to extend our support and change the foundation of our mission there to include capacity building for a joint operations center," Scheffer said, adding NATO would also be willing to help train troops headed to Darfur. "We are not talking about a NATO force on the ground in Darfur."

A request from the African Union would be required before NATO could increase its engagement in Darfur. That is currently being blocked by the Sudanese government, which is also blocking UN diplomats from entering Darfur to evaluate conditions for a UN peacekeeping force.

Slowing NATO expansion

Prolonging the expansion process for new NATO members without ruffling any feathers seems to be Scheffer's plan for dealing with the alliance's internal affairs.

"This is a discussion which is starting now in Sofia," he said, avoiding any particulars on whether Croatia, Macedonia, Albania, Ukraine and Georgia would be admitted to the alliance. "It is clear that NATO's door is open, that NATO supports reforms, but this is, as far as the aspirants are concerned, the important beginning of a discussion."

Scheffer added that expected a signal would be sent to the aspirant countries but admitted he did not know what that signal would be before the talks conclude.

Under pressure from the United States, the ministers will also address spreading the alliance farther to include anti-terrorism cooperation with Asian and Pacific countries.

Australia, Japan, New Zeeland and South Korea have all expressed interest in closer ties with the Brussels-based alliance, but Scheffer said enhanced cooperation with the nations would not turn NATO into a global entity.

"This is not making NATO into a global alliance, but it is making NATO into an alliance with global partners because the threats and challenges are of a global nature," he said.

Some NATO members, including Germany, France and Poland, had expressed their concern about expanding the North Atlantic Treaty Organization over too large an area.