Iraq and Syria have confirmed they have fully restored diplomatic relations after they were severed 24 years ago.
The agreement was announced in Baghdad by Walid Moallem, the Syrian foreign minister, who earlier called for a timetable for the withdrawal of US troops from Iraq, and Hoshyar Zebari, the Iraqi foreign minister.
Relations between the two countries were severed in 1982 when Damascus accused Baghdad of fuelling riots by the banned Muslim Brotherhood in Syria.
Moallem's visit to Iraq, which began on Sunday, has been the first official visit by a Syrian minister since Saddam Hussein's regime fell in 2003.
Ali al-Dabbagh, an Iraqi government spokesman, said: "The latest talks between the Syrian and Iraqi side have been crowned by declaring a new era with the participation of the Syrian brothers in working on the security and stability with Iraq and restoring full diplomatic ties."
"Iraq's security is part of our security"
Walid Moallem, the Syrian foreign minister
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Moallem met Iraqi officials, Nuri al-Maliki, the prime minister, and Jalal Talabani, the president, during his visit.
Zebari had earlier said that the visit would open "a new page in relations between the two countries".
'Brothers in Iraq'
Moallem earlier called on Iraqis to put aside sectarian and ethnic divisions and pledged Syrian support.
He said: "We are exerting all our efforts and understand that Iraq's security is part of our security. We will co-operate and we have specific ideas to discuss with the brothers in Iraq in order to set up this co-operation."
US and British authorities have claimed that Syria is funding armed Sunni groups in Iraq, an accusation Syria refutes.
Syria has also been accused of allowing fighters to cross its border with Iraq and the US has claimed that Syrians make up the second-largest group of foreign fighters entering Iraq after Egyptians.
Syria says sealing the border is impossible and that Iraq must do more to patrol its side.
The US military said on Monday that between 70 and 100 foreign fighters cross the border each month.
The two governments agreed to restore full diplomatic ties and to reopen their embassies in Baghdad and Damascus and Zebari and Moallem signed an agreement in the presence of journalists.
In the document, Syria and Iraq agreed on the need for US-led forces to stay in Iraq until they were no longer needed, after which they would be gradually withdrawn.
Gordon Johndroe, a US national security council spokesman, said in a statement: "We have always encouraged Iraq's neighbours to take a role in supporting and assisting the unity government in Iraq.
"Syria needs to now demonstrate that it is committed to constructive engagement and fostering an Iraq that can govern, sustain and defend itself.
"One of the first steps Syria could take is to strengthen its border with Iraq and stop the flow of foreign fighters into that country."