Exports of crude oil from northern Kirkuk oil fields have been on hold for the last three days due to an explosion at a key pipeline in Iraq , two Middle East shipping agents said Monday.

"The pumping of crude oil from
Kirkuk has been on hold since Friday at 2300 local time," a shipping agent based in Turkey 's Ceyhan port in the Mediterranean told The Wall Street Journal.

A second shipping agent confirmed that the flow has been on hold.

Iraqi oil officials were not available to comment.

"We are hearing that there was an explosion at part of the export pipeline inside
Iraq ," the first shipping agent said.

Iraq normally exports an average of 300,000 to 350,000 barrels a day but sabotage against the pipeline over the last few months, has reduced the flow. Last month, Iraq exported 273,000 barrels a day via the pipeline due to damage to the pipeline by unknown attackers.

Iraq 's crude oil exports in May were down 5.4% to 2.480 million barrels a day, versus 2.622 million barrels a day in April due to bad weather in the southern oil terminals in the Gulf and attacks on the northern oil export pipeline to Turkey , the Iraqi oil ministry said in a statement Sunday.

The Iraq-Turkey pipeline that carries crude from
Kirkuk oil fields to Ceyhan has frequently been attacked, sometimes in Turkey but mostly in Iraq . The pipeline was idle for many years due to acts of sabotage after the U.S.-led invasion in 2003.