Followers of radical Iraqi Shia cleric Moqtada Sadr say they have rescued four hostages from their kidnappers hours before they were to be killed.
The freed hostages were from Syria, Lebanon and Iraq
Members of Mr Sadr's Mehdi Army freed the four Arab hostages from "terrorist groups" holding them in Baghdad, an aide to the cleric said.
At least five Iraqis were reportedly killed in attacks, and the brother of a minister shot dead, on Friday.
Politicians are continuing tense talks to agree a draft constitution.
The issue of federalism and distribution of resources such as oil revenues are proving the most contentious issues.
A BBC correspondent in Baghdad says it is hard to see how a consensus will be achieved before Monday's deadline.
An aide of Mr Sadr, Sheikh Abdel Zahra Suwaidi, said in a sermon on Friday that the cleric's militia group had helped in the release of the hostages.
"Members of the Mehdi Army have freed some Arab and Iraqi hostages, kidnapped by terrorist groups who were planning to kill them in the coming hours," he was quoted as saying.
The freed men identified themselves to an Associated Press photographer as Syrian Hisham Salem, Lebanese Mustafa Abdul-Rassoul Hussein, dual Syrian-Lebanese citizen Atta Ibrahim and Iraqi Kurd Haji Alawi.
A spokesman for Mr Sadr, Amer Husseini, was quoted by AP as saying the men were freed on Thursday night during a raid on an apartment in the northern district of Shaab.
He did not say what happened to the kidnappers or why the men had been seized in the first place.
In other violence, three Iraqi civilians and a soldier were killed in clashes between a US-Iraqi patrol and insurgents in Samarra, north of Baghdad, said Iraqi army sources.
Just north of Samarra, a civilian was killed and two others wounded when a roadside bomb exploded near their car.
In a southern district of Baghdad, the brother of Azhar Shaikhly, state minister for women affairs, was killed by gunmen, it was reported.