With maritime traffic through the Strait of Hormuz disrupted, Iraq's exports came to a halt and oil storage tanks began filling up rapidly, forcing Iraqi authorities to largely suspend production.

At the beginning of April, Iraq announced it had started transporting oil by truck through Syria in preparation for re-export by boat.

"The loading of the first oil tanker is underway in Syria today, under the agreement reached with the Iraqi side to transport Iraqi oil to the Baniyas refinery and then to the oil terminal for shipment by sea," Syrian Petroleum Company deputy CEO Ahmed Qubbaji told reporters.

"The quantity that will be loaded onto the tanker is estimated at around 500,000 tons" and the loading operation will take at least three days, he said.

According to Qubbaji, the agreement allows Syria to take "the oil we need for power plants in order to generate electricity, while the surplus is exported".

An AFP correspondent saw dozens of trucks with Iraqi license plates at the entrance to the city of Tartus, heading towards the Baniyas refinery and the storage tanks surrounding it.

The Iraqi oil ministry said in early April that it had begun exporting oil by truck through neighbouring Syria.

A founding member of the OPEC oil cartel, Iraq is hugely dependent on its oil exports, accounting for some 90 percent of its budget revenues.

Before the start of the Middle East war on February 28, most of its output -- roughly 3.5 million barrels per day in normal times -- had been exported via the Gulf.

Last month, Iraq announced it had resumed part of its exports, up to 250,000 barrels per day, through the Kurdistan region's oil pipeline that runs to Turkey's Ceyhan port.