"All of the money belongs to Iraq. An Iraqi delegation will travel in the next few weeks to Damascus," Kamil al-Gilani, finance minister in Iraq's US-backed provisional government, told journalists in Baghdad on Wednesday.
In Damascus, an official Syrian source said the figure was not accurate, saying it amounted to hundreds of millions of dollars, not billions.
The $3 billion amounts to almost 30% of Syria's gross domestic product and is slightly less than Iraq's self-generated liquid funds, which are controlled by the United States.
Gilani said Syria accumulated the money by selling oil on behalf of Iraq in contravention of UN sanctions and selling non-military goods to the Iraqi Military Industrialisation Organisation, which was under the direct control of former Iraqi leader, Saddam Hussein.
Syria says amount it owes Iraq is
in millions, not billions
"We do not recognise these deals," he said.
The Iraqi oligarchy, such as Saddam's family and their agents, also deposited money in regional banks, Gilani said.
"These private deposits belong to Iraq and must be recovered. They are certainly in the millions and possibly billions," Gilani said.
But Syria questioned the figure. "The amount (Iraqi assets) is in hundreds of millions of dollars. This has been made clear to an Iraqi delegation who visited for talks on the assets," the official source said in Damascus.
"There is an ongoing clearing process... there are amounts owed to Syrian businessmen who had business transactions with Iraq and have not been paid," the source added.
Syria has been a political enemy of Iraq for decades and does not recognise the present Iraqi government.
Saddam Hussein was forced to resume relations with Damascus after Jordan - Iraq's main outlet to the world - turned against Baghdad after the 1990 Gulf War, eventually backing the US invasion.
"These private deposits belong to Iraq and must be recovered"
US-backed Iraqi government
Iraq started pumping oil to Syria through a pipeline in recent years, border movement was eased and Syrian consumer products flooded the Iraqi market. Syria has argued that the pipeline that had been shut for two decades was being tested and not used commercially.
Iraq's banking, however, was still mainly conducted through Jordan and Lebanon. Gilani said the first instalments of $1 billion of Iraqi government and central bank assets held in Jordan and Lebanon would start flowing to the Iraqi central bank in a matter of weeks.
"We agreed to transfer the money in instalments to help preserve our neighbours' banking strength," Gilani said.
Syria keeps a careful watch over Lebanese politics and Beirut's readiness to hand over Iraqi assets could indicate willingness by the Syrian authorities to cooperate when the Iraqi financial delegation visits.