Neither Iraqi Prime Minister Nuri al-Maliki nor US ambassador Ryan Crocker attended the meeting at the Foreign Ministry inside the heavily fortified "Green Zone" government and diplomatic compound in central Baghdad.
"We've been having talks today between two negotiating teams," US embassy spokesman Phil Reeker said.
Mr Reeker did not say when Mr Maliki and Mr Crocker might begin formal talks on the pact.
The talks will focus on security and future US military, diplomatic and political relations between Baghdad and Washington, as well as economic and cultural ties.
Iraq's Foreign Ministry said the talks would aim to "find a basis for long-term friendly relations between both countries, including a temporary agreement for the presence of American forces in Iraq".
"The talks will be based on the mutual interests and respectful exchanges between the two countries," he said.
The substance of the pact has become a politically charged issue in Washington, with members of Congress protesting against the administration's intention to negotiate the future relationship with Baghdad and saying they should be consulted.
Democrats say the agreement on US forces could lock the United States into a long-term military presence in Iraq. US President George W. Bush's administration said it is a routine measure to govern the legal status of US troops.
The talks were to have begun last month. US and Iraqi officials in Baghdad said they hope to reach an agreement by July, well before the next US president is elected on November 4.
"These negotiations will continue until they are finalised in the summer of this year," the Iraqi Foreign Ministry said.
US forces operate in Iraq under a United Nations mandate that expires at the end of 2008. Iraq does not want that mandate extended, so the two governments must agree guidelines to allow US forces to remain beyond the end of this year.
