The official Syrian news agency SANA confirmed Syria would attend.
"There will not be bilateral talks between the United States and Iran, or the United States and Syria, within the context of these meetings," Tony Snow, White House spokesman, told reporters.
"We are not engaging in diplomatic recognition of Iran. We are not engaging in bilateral talks with Iran," he said.
But, he added, "There are multilateral forums where, if the Iranians are there, we're not going to walk out."
"I believe there is a widely available diplomatic solution that the people of both America and Iran want"
thesavior, Edmonton, Canada
Al-Maliki's office said on Wednesday he had formally sent invitations to the meeting to neighbouring countries, Egypt, the five permanent members of the UN Security Council - the United States, Russia, China, Britain and France - as well as the Arab League and the Organisation of the Islamic Conference.
"We hope the meeting will bring political backing for the national unity government in providing security and stability that will help national reconciliation in Iraq," the prime minister's office said in a statement.
Ali Larijani, secretary of Iran's Supreme National Security Council, said Tehran was weighing the invitation.
Iranian officials had previously said Tehran was not interested in discussions before US troops pulled out of Iraq.
"In order to help resolve problems in Iraq, Iran will do its utmost. We will attend the meeting if [we reach the conclusion] that it is in Iraq's interests," Larijani was quoted by Iran's state television as saying.
The regional meeting comes after the United States accused Iran of supplying Iraqi fighters carrying out attacks on US forces and contributing to the country's sectarian violence.
|The US has accused Iran of supplying |
Iraqi fighters with weapons [AFP]
Snow said these issues would not be avoided.
"If, in fact, topics like EFPs [explosive formed penetrator projectiles used against US forces] and such come up in that conference, obviously we will address them," he said.
A Syrian foreign ministry official told SANA: "Talking with the United States about Iraq is a partial step in the right direction. All the problems in the region are interlinked."
The White House said US officials had previously joined regional meetings attended by Iran and Syria without changing its position towards either.
"The United States in a number of forums in the recent years has been at the table along with Iran and Syria without changing its bilateral position towards either," Snow said.
He added that Tehran would have to change its policies before Washington would deal with it directly.
Hoshiyar Zebari, the Iraqi foreign minister, said the initial mid-level meeting would be a chance for Western and regional powers to try to bridge some of their differences on Iraq. A ministerial meeting is expected in April, Washington has said.
Tareq al-Hashemi, the vice president and a leading figure for Iraq's Sunni Arabs, met Iran's ambassador on Wednesday and his office said he would visit Tehran in early March.