The flow of oil on Iraq's main pipeline to Turkey was halted for a third day on Sunday after a technical problem on the Iraqi side was compounded by a bomb attack by suspected PKK rebels in Turkey.
The bombing by PKK on Saturday night added a new dimension to the threats against the pipeline, which carries around a quarter of Iraq's oil exports, after the rebel group called off a 14-month ceasefire in June.
The explosion took place near the town of Midyat in Mardin province, near the border with Syria, Turkish security sources said.
Crew workers from Turkey's state-run pipeline operator BOTAS were still working on Sunday night to fix the damage. The flow of oil might resume on Monday, the sources said.
On the Iraqi side of the border, technicians managed to resolve a problem which halted pumping late on Thursday and had started pumping at test levels on Sunday evening, sources at Iraq's North Oil Co. said.
The 960 km (600 mile) pipeline carries an average of 500,000 barrels of oil per day from Iraq's northern oilfields around Kirkuk to Turkey's Mediterranean port of Ceyhan, where it is loaded onto tankers for export.
Sabotage and technical problems kept the Iraq-Turkey route mostly idle until 2007 following the 2003 U.S.-led invasion of Iraq.
Security has improved but insurgents still target the pipeline and it also suffers frequent technical issues because of its age and poor maintenance over the years.
Attacks on the Turkish side of the border had to date been far less common.