The session opened as at least 60 people were killed in two deadly attacks by suspected Sunni Arab insurgents in and around Baghdad.
"The gates of hell are open in Iraq," Mussa said, voicing hope that Arab foreign ministers could "help Iraq through this crisis, re-establish sovereignty throughout the country and end the American occupation."
His comments echoed a declaration by French President Jacques Chirac, one of the most vocal opponents to the US-led war in Iraq, who compared the situation there to a Pandora's box.
At least 47 people were killed in a massive car bomb blast outside the main police headquarters in Baghdad on Tuesday, while 12 policemen and their driver were killed by gunmen in Baquba, north of the capital.
During its two-day meeting, the Arab League is due to debate a draft resolution giving a blanket condemnation of violence against police or civilians.
Ministers "condemn all forms of terrorism in Iraq targeting civilians, police, security force personnel and journalists, as well as diplomatic missions and humanitarian or religious groups bringing aid to the Iraqi people," said the draft, a copy of which was obtained by AFP.
Two French journalists and two Italian women aid workers are currently being held hostage by insurgents in Iraq.
The draft also calls on the Arab League's 22 members to restore diplomatic relations with Iraq to the level they were at before last year's invasion "in order to bolster the political efforts being exerted by the interim Iraqi government".
The text urges Arab governments to provide training for Iraqi government personnel "including members of the police and security forces" and to speed up dispersal of promised aid for the country's reconstruction.
Relations with Iraq's US-backed interim government have been divisive issue in the Arab world, with some capitals leaning towards the Iranian position of disparaging the unelected administration as a creature of the United States.
Syria has been specifically accused by US officials of failing to do enough to stem infiltration by militants across its border with Iraq. Would-be fighters have also slipped in from Saudi Arabia, US commanders say, while in Kuwait a suspected recruitment ring for foreign volunteers is currently on trial.