With no release on Thursday, Rome has tried to stamp out rumours it had paid a €5 million ransom to have them freed.
Prime Minister Silvio Berlusconi said on Wednesday a ransom "hasn't even been talked about".
But speculation about the situation has grown after he admitted "there has been a delay" in their release.
Berlusconi sparked a flurry of excitement late on Tuesday among the captives' relatives and reporters camped outside their houses.
He said he was confident there would be news "in the coming hours" on the captives' release.
And rumours of a ransom, reported and then denied by a senior Italian official in Iraq, Barbara Contini, have added to the confusion.
The governor of the Iraqi province of Dhi Qar, Contini appeared to confirm money had been handed over.
When asked by a TV reporter if "even in this case money was paid", she responded "yes". However she later claimed she meant "there is always a price to pay in these situations".
Hostage already killed
The captors have already killed one of four private security workers seized last week.
They say they will kill the other three unless Italy withdraws a contingent of 2700 troops forming part of the US-led force occupying Iraq.
The prime minister has refused to budge on the troops issue, saying Italian soldiers would stay in Iraq even after the planned 30 June handover of power to a selected Iraqi government.