Iraqi Foreign Minister Hoshyar Zebari said he will be issuing formal invitations shortly to the neighboring countries and the five permanent U.N. Security Council members ¡ª the U.S., Britain, France, Russia and China ¡ª to send deputy foreign ministers or senior officials to the meeting.

Zebari, in a telephone interview with The Associated Press from Sweden, said Iran has agreed to participate in the meeting with the other neighbors but "they have some questions" about a meeting that would be held the same day with the five permanent council members.

His words seemed to indicate that Iran was at least partly unhappy with the arrangements for the meeting, and weighing the extent of its own participation.

Iran has had little public comment on the meeting so far. But in the past, Iranian leaders have been vocal in accusing the United States of trying to use the U.N. as a way to "gang up" on it, and the presence of the key Security Council countries at the Iraq meeting might give Iran pause.

For their part, Sunni Arab countries like Egypt still hold grave concerns about the direction taken by Iraq's Shiite-led government, raising concerns the conference will make little headway on key issues like security.

Iraq's relations with its Arab neighbors have been rocky because of fears that the Shiite-led government is falling under Iran's influence. Originally, the Iraqi government had been reluctant to endorse the regional conference, fearing pressure from Sunni-dominated regimes, but it dropped those objections last year so long as the gathering was held on Iraqi soil.

Two Arab diplomats in Cairo said Wednesday that the U.S. recently increased pressure on some Arab governments to press them to attend the meeting, after they initially had turned down invitations from the Iraqi government. They spoke on condition of anonymity because of the issue's sensitivity.

The March meeting got a big boost Tuesday when Washington said it would attend, leading to the possibility it could discuss Iraq's security with adversaries Syria and Iran.

The Bush administration had waited to embrace the idea until Iraq made progress on a deal governing national distribution of oil revenue. The difficulty in getting such a deal is symbolic of Iraq's regional, factional and political divisions, and the deal was seen by the United States as a key marker of the government's will to work across divides.

"They thought the timing was right for them to hold the conference, and so we encouraged them to move forward with it," State Department spokesman Sean McCormack said Wednesday.

U.N. Secretary-General Ban Ki-moon is sending the U.N. envoy in Iraq, Ashraf Qazi, to attend the meeting as an observer, U.N. spokeswoman Michele Montas said.

"The secretary-general hopes that the participants in the preparatory meeting will focus on urgently needed steps to reduce violence in Iraq and help stabilize the situation in the region," Montas said.

Iraqi Deputy Foreign Minister Labid Abawi said the United States, Britain, China, Saudi Arabia and Iran said they will attend.

"The conference will be important. It will prove that Iraq is politically capable of holding such a conference. It will send a message to the world," said Prime Minister Nouri al-Maliki's adviser, Sami al-Askari.

Syria and Egypt confirmed separately they would attend, but there was no immediate comment from Jordan or Saudi Arabia. Bahrain, Turkey and Kuwait were also invited, along with the Arab League and the Organization of the Islamic Conference.

Arab countries had been reluctant to accept an invitation previously, because of Iraqi security issues as well as their hesitancy to be seen as supporting the Baghdad government by attending the gathering there, Arab diplomats said.

Iraq and its neighbors have held nine meetings, Zebari said. At the last meeting, in Tehran in July 2006, Zebari said "I demanded that the next meeting should be in Iraq. ... I told them we are capable, we are confident, we can ensure your security."

Asked about Iran's participation in the conference, a spokesman for Iran's U.N. Mission sidestepped the question:

"We believe if the United States really wants to reach a solution there is hope that they can achieve that," the spokesman said on condition of anonymity because he was not authorized to speak publicly.

Ali Larijani, the head of Iran's Supreme National Security Council, said it was important to involve Iraq's neighbors.

"We believe Iraq's security is related to all its neighboring countries, and they have to help settle the situation," Larijani said.

But Mustafa Alani, an expert in Iraqi affairs at the Gulf Research Center in Dubai, said while the meeting will officially focus on Iraq's security, neighboring Sunni Arab countries and the U.S. will use it to convey their disquiet at Iranian influence.

Each side has accused another of being responsible for the spiraling violence in Iraq. The U.S. claims Iran is sending weapons and money to Shiite extremists in Iraq. Iraqi officials, meanwhile, have complained that Syria harbors former Saddam Hussein loyalists and allows weapons and foreign fighters to slip into the country, while Sunni countries believe the fault lies with Iraq's Shiite-led government.