Unidentified attackers fired mortar shells on Sunday night at the pumping station 25km west of the oil-rich city of Kirkuk which feeds the internal and export pipeline network to Turkey and Syria, said Abd al-Karim al-Juburi, a security official.
  
Iraqi police also said they arrested four Iraqis who planned to launch a rocket attack against US occupation forces based at Kirkuk airport and to blow up a giant fuel reservoir near Iraq's largest refinery at Baiji, 180km north of Baghdad.
  
A US military spokeswoman in Baghdad said she had no information on the Kirkuk incident.
  
Earlier, the US military denied reports of an attack on a pipeline between Baiji and Tikrit, hometown of captured ousted leader Saddam Hussein, and said the fires raging there were the result of burning "residual fuel".
  
Three anti-tank rockets hit a pipeline south of Baghdad on Friday night causing a "significant" leakage, according to Asam Jihad, spokesman for Iraq's interim oil minister Ibrahim Bahr al-Ulum.
  
Jihad also said that an explosive device hit a pipeline in the Mashahda region, 50km north of the capital.

More rationing? 
  
The attacks have limited the output of the central refineries, already operating at half their capacity, said Jihad. 

Motorists say the petrol station
queues can stretch for 3km

As of Sunday morning the number of sabotage acts against Iraq's oil infrastructure since Saddam's fall in April stood at 86, according to Jihad, who said they were the main reason behind fuel shortages plaguing the country.
  
Ordinary Iraqis are struggling to obtain fuel and cooking gas as they face frequent power cuts and motorists still line up for petrol.

Iraq's oil ministry announced restrictions on petrol distribution last Wednesday, just one week after rationing went into effect at fuel stations in the country, home to the world's second largest oil reserves.

Motorists are now allowed 30 litres each, compared with 50 litres previously.

On 10 December, the ministry restricted purchases to 50 litres each, at a price of 20 dinars (one cent) each, in an effort to curb lengthy queues at filling stations.