Crews are repairing a main pipeline feeding southern terminals that was sabotaged last week, halving oil exports, officials and shipping agents said on Monday.
Forecasts ranged from one to four days on when the repairs would finish and pumping could restart.
Iraq had been exporting nearly two million barrels per day (bpd) from two offshore Gulf terminals before the weekend sabotage on the smaller of two pipelines supplying them.
Export flows were running on Monday at 984,000 barrels per day to the Basra terminal, formerly known as Mina al-Bakr. No tankers loaded from the nearby Khor al-Amaya terminal for the third day.
The Astro Cassiopeia, was loading from Basra platform number four at a rate of 41,000 barrels per hour. The other platforms were empty, an international shipping agent said.
Saboteurs also attacked the pipeline linking the country's northern and southern oil fields on Sunday, setting a section of it on fire.