"We are making some progress. There is no date set yet," Rob McKee, the authority's oil chief, told Reuters.

"The fact is that there are some wonderful oilfields in the north. It is important to figure out a way to export the northern crude."

Oil infrastructure sabotage has been rare in Iraq's mostly Muslim Shi'ite south, but Iraq's main internal pipeline was on fire Monday after coming under attack a few days ago near the Shi'ite holy city of Kerbala.

One option U.S. and Iraqi oil officials were considering was to use the line, known as the strategic pipeline and currently out of commission, to pump Kirkuk crude south for export from the Gulf.

But a guard in the region said an explosive device ripped through a section of that link about a week ago.A Reuters photographer saw smoke still rising Monday from the reversible line west of Kerbala.

Attacks have mainly targeted the export pipeline from Kirkuk oilfields to the Turkish port of Ceyhan which runs through Muslim Sunni strongholds, co-religionists of former Iraqi president Saddam Hussein.

Starting the pipeline is crucial for raising Iraqi oil export capacity because the southern Basra offshore terminal is running at full capacity.

Iraq is reinjecting as much as 400,000 barrels a day of Kirkuk crude back into reservoirs because it cannot export the oil. Exports are restricted to the south and now are running near 1.6 million bpd.

Baghdad had hoped to restart the Kirkuk line, pumping about 800,000 bpd before the U.S. invasion, by the end of March.  

Officials from Erinys, a South African company awarded a contract to protect the Kirkuk pipeline, said sabotage attacks were still common, despite having enlisted local tribes to guard the facility.

"We are seeing regular attacks around the pumping station and further north in Hadar," said a security official who spoke on condition of anonymity.

He was referring to the IT-A1 pumping station near the village of Makhul in northern Iraq, an area littered with communication towers, Iraqi rockets and other arsenal destroyed by U.S. bombardment a year ago.

Almost all of the security guards in the area are from the Shumar tribe, one of the old northern Sunni clans that formed the bedrock of support for Saddam.

The pipeline runs through areas that have been leading resistance against the U.S. occupation, such as Hawijah near Kirkuk. Oil that leaked from sabotaged sections lies in pools next to the pipeline.

The 40-46 inch pipeline is mostly underground but can be easily traced.

It starts in the Kirkuk oilfields, crosses a mountain range and the main highway to Turkey before reaching the Makhul pumping station, from where the crude is pumped across the Turkish border.

A new section of pipe appeared to be under construction just before the pumping station.

Issa Hussein, manager of a local petrol station on the highway, said the last explosion he saw was around 10 days ago.

"The resistance fighters are daring," he said. "But they are losing support by sabotaging the infrastructure."