The decision on Sunday night came amid increasing sectarian violence in Iraq.
The Arab committee on Iraq agreed that Mussa would make the trip as soon as possible to meet factions and "prepare for an inclusive Iraqi national reconciliation conference", Saudi Foreign Minister Prince Saud al-Faisal said after a meeting in Jeddah.
The conference will be held under Arab League auspices, al-Faisal said.
Mussa would go to Iraq "very soon", he said when asked whether the visit would precede a 15 October referendum on a draft constitution that has sharpened sectarian rifts in the violence-ravaged country and is opposed by Iraq's once-dominant Sunni Arabs and many Shia as well.
Al-Faisal had opened the gathering with a call for organising a meeting of all Iraqi factions to promote consensus on the draft constitution.
"In light of the outcome of [Mussa's] visit, an Arab strategy on Iraq will be drawn up and submitted to the league's ministerial council [of foreign ministers] in the near future," the prince said.
US hails move
The State Department welcomed the Arab League initiative to promote reconciliation in Iraq among the country's deeply divided factions.
Department spokesman Sean McCormack called the Arab League action, taken at a conference in Saudi Arabia, a "positive development".
"We have urged Iraq's neighbours as well as other countries in the region lend their diplomatic support to the Iraqi people and the Iraqi government," he said on Monday.
"This step is timely. We think it's important to do so, not only rhetorically but with a presence there," he added.
He said the United States has been urging Iraq's neighbours for some time to think about sending diplomatic missions and a diplomatic presence to Iraq.
There was no mention of dispatching Arab observers to monitor the referendum and national elections in December, a possibility raised before the ministerial committee met in Jeddah for the first time since it was created by the Arab League in September.
Foreign Minister Saud al-Faisal
called for the factions to meet
The committee groups Algeria, Bahrain, Egypt, Iraq, Jordan, Kuwait, Saudi Arabia and Syria.
All members were represented by their foreign ministers except Algeria, which sent presidential envoy Abdelaziz Belkhadem.
Most Sunni organisations have urged a no vote, mainly because they distrust federal provisions in the draft, which they view as imposed by the Shia and the Kurds.
Al-Faisal also announced that Iranian Foreign Minister Manouchehr Mottaki would visit Saudi Arabia on Wednesday for talks on the situation in Iraq.
The announcement comes days after the Saudi chief diplomat had publicly expressed concern at purported Iranian meddling in Iraq's affairs.
His remarks reflected Riyadh's concern that Shia Iran has increased its influence in Iraq, where it enjoys sympathy among the now-ruling Shia-led government at a time when Sunni Arabs feel marginalised.
Al-Faisal's comments on alleged Iranian meddling and sectarian divisions in Iraq drew a scathing attack from Iraq's Interior Minister Bayan Baqer Sulagh, who told reporters in Amman on Sunday that he would not take lessons from "a beduin on a camel".
Iraqi Interior Minister Bayan
Sulagh criticised al-Faisal
But Sulagh, a Shia, was publicly rebuked by Iraqi Foreign Minister Hoshyar Zebari.
"These statements are extremely regrettable ... coming from a colleague of ours in government," Zebari said.
"We hold the kingdom [of Saudi Arabia], and particularly Prince Saud al-Faisal, in high esteem," he added.
Participants in the meeting had earlier said that Zebari apologised for the anti-Saudi tirade.
Effective Arab role
Zebari also said he had put to the meeting an Iraqi paper outlining "the need for an effective and influential Arab role in Iraq, particularly at this transitional stage".
He said it had been agreed that Mussa would "meet political leaderships and the government [in Iraq] with a view to achieving national entente and reconciliation," after which Arab League foreign ministers would decide their next step.
"In light of the outcome of [Mussa's] visit, an Arab strategy on Iraq will be drawn up and submitted to the league's ministerial council [of foreign ministers] in the near future"
Saudi foreign minister
An Egyptian diplomatic source said Egyptian President Hosni Mubarak would visit Saudi Arabia on Monday for talks with King Abdullah on Iraq, as well as the Palestinian issue.
There are fears of an upsurge in violence with two weeks to go before Iraqis vote on a post-Saddam Hussein constitution.
Government statistics indicate that the number of Iraqis killed in attacks rose to 702 in September from 526 in August. Most of those killed were civilians.