Syrian president Bashar al-Assad is growing increasingly isolated after Iraq and Lebanon distanced themselves from his troubled regime.
Iraq's Prime Minister Nuri al-Maliki said: "Iraq backs change in Syria. Change is necessary. The situation will not be stable without change."
He said a national unity government was the first step under Arab and UN supervision.
Despite the recent referendum on a new constitution, Maliki said "a national council must be chosen which will write a new constitution".
Iraq had shied away from coming out against Assad but the tide against him is turning as the vicious crackdown on protests nears its first anniversary.
Lebanon's Prime Minister Najib Mikati has also distanced himself from Syria and gone for a policy of "disassociation".
He told the Egyptian Al-Jumhuriya newspaper: "It is best that we dissociate ourselves regarding Syrian [developments]."
"We dissociate ourselves politically but we do not dissociate ourselves [when] our Syrian brothers' needs [are concerned]," he added.
Mikati came to power last year with the backing of Hezbollah and stopped short of calling for regime change.