Iraqi Prime Minister Nouri al-Maliki formally authorized Syrian refugees to enter Iraq, according to the Associated Press, which cited Iraqi state television.
Thousands of Syrian refugees have sought shelter in neighboring Jordan, Iraq, Lebanon and Turkey, especially since fierce fighting began in Damascus.
However, as recently as last Friday, the Iraqi government was reluctant to take in Syrian refugees because "we cannot provide aid... and because of the security situation," said government spokesman Ali Dabbagh, according to Agence France Presse.
Iraq's transport ministry said more than 2,000 Iraqis had returned from Syria in addition to thousands who crossed the Al-Waleed border between the two countries.
More on GlobalPost: Tide of Syrian refugees swells
On the same day as opening its borders, Iraqi government spokesman Dabbagh rejected the Arab League's calls for Syrian President Bashar al-Assad to step down, saying that it was ultimately in the hands of the Syrian people, Reuters reported.
"The Iraqi delegation put forward their reservation. It is not usual for the ministerial council to ask someone to leave. This is the sole responsibility of the Syrian people and others should not interfere," he said.
More on GlobalPost: Arab League to Assad: Renounce power and get safe passage out of Syria
Reuters noted that the number of Syrians crossing into Iraq was lower than those flooding into Turkey and Lebanon. This is probably due to Baghdad's Shia-led government's close relationship with Assad. Iraq's approach to Syria has been more moderate than the Sunni Gulf nations of the Arab League.
The AP noted that during the worst years of the Iraqi insurgency, between 2005 and 2007, Iraqis sought refuge in Syria to escape the sectarian violence.