Iraqi officials have repeatedly warned that Iraq could suffer as Syria's security deteriorates.
In an interview with The Associated Press this week, al-Maliki predicted that a victory for rebels in the Syrian civil war would create a new extremist haven and destabilize the wider Middle East, sparking sectarian wars in his own country and in Lebanon.
The war in Syria has sharp sectarian overtones, with predominantly Sunni rebels fighting a regime dominated by Alawites, an offshoot of Shiite Islam. Rebel groups have increasingly embraced radical Islamic ideologies, and some of their greatest battlefield successes have been carried out by Jabhat al-Nusra, an al-Qaida-affiliated group which the U.S. has designated as a terrorist organization.
That is exacerbating rifts between Iraq's own Sunnis, whose members held many senior positions in Saddam Hussein's regime, and the Shiites whose sect rose to prominence following the March 2003 U.S.-led invasion.
Earlier Friday, two car bombs struck a livestock market south of the Iraqi capital, killing five and wounding dozens in what was the second such attack in as many days.
The twin bombing targeted the market in the Shiite city of Diawaniyah, 130 kilometers (80 miles) south of Baghdad, at the height of trading when many people pour into the market at the start of the weekend.
The head of the provincial council, Jubair al-Jabouri, said five people were killed and 70 were wounded in the attack. He blamed the blasts on al-Qaida, though there was no immediate claim of responsibility.
A day earlier, a similar attack tore a crowded livestock market in the town of Aziziyah, also south of Baghdad, killing three and wounding eight people.
Violence in Iraq has fallen since the height of sectarian fighting in 2006 and 2007, but deadly attacks are still frequent. On Thursday, bombings in Baghdad, Aziziyah and another town south of the Iraqi capital killed at least 22 people.
Associated Press writer Adam Schreck contributed.