Iraqi Prime Minister Nouri al-Maliki opened the conference with an appeal for all participants to help ease his country's plight and prevent the violent conflict here from spilling over into the entire Middle East.
But the conference underscored the wide gulf between American and Iranian views over the nature of the crisis and the ways to end it.
During the talks, U.S. envoy David Satterfield pointed to his briefcase which he said contained documents proving Iran was arming Shiite Muslim militias in Iraq.
"Your accusations are merely a cover for your failures in Iraq," Iran's chief envoy Abbas Araghchi shot back, according to an official familiar to the discussions who spoke on condition of anonymity because he was not authorized to release the information.
The U.S. ambassador to Iraq, Zalmay Khalilzad, only said that American delegates exchanged views with the Iranians "directly and in the presence of others" during talks, which he described as "constructive and businesslike."
But Labid Abbawi, a senior Iraqi Foreign Ministry official who attended the meeting, confirmed that an argument broke out between the Iranian and American envoys. He would not elaborate.
Before the talks, U.S. officials said the Baghdad conference would allow all sides to spell out their positions frankly and pave the way for more substantive discussions on resolving the Iraq crisis.
Al-Maliki, a Shiite, appealed for international help to sever networks aiding extremists and warned that Iraq's growing sectarian bloodshed could spill across the Middle East.
Khalilzad also urged nations bordering Iraq - which include Syria and Iran - to increase their assistance to al-Maliki's government, saying "the future of Iraq and the Middle East is the defining issue of our time."
"(Iraq) needs support in this battle that not only threatens Iraq but will spill over to all countries in the region," al-Maliki said.
Al-Maliki urged for help in stopping financial support, weapon pipelines and "religious cover" for the relentless attacks of car bombings, killings and other attacks that have pitted Iraq's Sunnis against majority Shiites.
Underscoring the security crisis, at least two mortar shells exploded near the Foreign Ministry where the talks were held but caused no casualties. A suicide car bomber also killed 20 people in the Shiite militia stronghold of Sadr City.
The participants at the talks included all of Iraq's neighbors - Iran, Syria, Jordan, Saudi Arabia, Turkey and Kuwait - as well as the U.S., Russia, France, Britain, China, Bahrain, Egypt, the U.N., the Organization of the Islamic Conference and the Arab League.
At a news conference after the meeting, Araghchi restated Tehran's demands for a clear timetable for the withdrawal of U.S.-led forces, which he insisted had made Iraq a magnet for extremists from across the Muslim world.
"For the sake of peace and stability in Iraq ... we need a timetable for the withdrawal of foreign forces," said Araghchi, Iran's deputy foreign minister for legal and international affairs.
"Violence in Iraq is good for no country in the region," he said. "Security of Iraq is our security and stability in Iraq is a necessity for peace and security in the region."
Araghchi said he had no face-to-face, private talks with Khalilzad and that the discussions were "within the framework of the meeting." He spoke of "very good interaction by all the delegations."
Khalilzad, too, called the meeting a "first step."
"The discussions were limited and focused on Iraq and I don't want to speculate after that," said the Afghan-born Khalilzad, who greeted Araghchi in the Persian language.
Nevertheless, the discussions illustrated the deep differences between Tehran and Washington, although each insists that full-scale civil war is in neither country's interest.
"Regarding security, we have channels that we can put to use," Araghchi told The Associated Press. "We are ready for any help we can give to Iraq."
Reza Amiri, a senior official at the Iranian Foreign Ministry, dismissed American claims that Tehran was destabilizing Iraq by arming Shiite militias. The U.S. military has insisted that Iranian weapons, including a new generation of powerful roadside bombs, have killed more than 170 U.S. and coalition troops here since mid-2004.
"They're lying because it is just not true," Amiri told the AP. "Iraq's borders with Iran are the most secure of Iraqi borders. The Iraqi government has not even once said Iran is interfering in its affairs."
But Amiri said Saturday's conference was "very positive" because "everyone promised to cooperate with each other and to control the borders."
The delegates proposed an "expanded" follow-up meeting, which could include the G-8 nations and others, in Istanbul, Turkey, next month. Iraqi officials, however, say they will urge that the next meeting take place again in Baghdad.
For Iran, opening more direct contacts with Washington could help promote their shared interests in preventing full-scale war between Sunnis and Shiites. Iran has influence among Shiite political parties with ties to militias.
The Baghdad talks come as the U.S. administration has toughened its rhetoric on Iran and flexed its muscles at the U.N. over Tehran's disputed nuclear program. The tough talk has been accompanied by the arrival of two U.S. carrier battle groups near the Iranian shores in the Persian Gulf.
Iranians increasingly fear that a U.S. attack is imminent despite American insistence to the contrary.
The U.S. and Iran severed diplomatic ties after Iranian militants seized the U.S. Embassy in Tehran following the 1979 Islamic revolution. In the late 1990s, U.S. and Iranian envoys were part of an eight-nation group studying Afghanistan's troubles under the Taliban, and both nations took part in meetings to establish an interim Afghan government after the Taliban's fall in 2001.
In 2000, a four-member U.S. congressional delegation met with Iran's parliament speaker, Mehdi Karroubi, and others for informal talks during a worldwide gathering of lawmakers in New York.
Iranian analyst Saeid Leylaz said the Baghdad conference would be a non-starter if it's not followed by a one-on-one dialogue between Washington and Tehran.
"How can you expect us to talk to them about Iraq's security without Iran's security being part of the talks?" said Leylaz.
He said only a "constructive and strategic dialogue between Tehran and Washington" would resolve the Iraq problem.
"Tehran could help temporarily in Iraq," said Leylaz, "but for an everlasting solution, talks should comprise of security guarantees for the whole region."
"The Americans must understand the question of security is a matter of life and death for Iran," he said. And nowhere is that security as vital for Iran as on its borders with Iraq.