The US administrator running Iraq, Paul Bremer, has warned that continuing sabotage attacks against the country's infrastructure will delay economic recovery.
Firefighters can do little to stop the two fierce blazes
Saboteurs have been blamed for a series of explosions that have damaged both oil and water pipelines in Iraq.
Two fierce fires are burning out of control within kilometres of each other along the country's main northern oil export pipeline - which had opened only days before the first blast hit it on Friday.
About 300,000 Baghdad residents, meanwhile, have been left without water after an explosion ripped through a water pipeline in the city on Sunday.
Mr Bremer said the damage to the oil pipeline would cost Iraq $7m a day and "hurt the process of reconstruction".
"The irony is that Iraq is a rich country that is temporarily poor," he told the meeting of a committee coordinating foreign aid for Iraq.
Officials have said there is little they can do to fight the pipeline blazes except shut off the oil and wait for them to burn out.
In other developments:
- Six Iraqis are killed and 59 injured in a mortar attack on Abu Gharib prison on the outskirts of Baghdad
- A Reuters cameraman, Mazen Dana, was shot dead while filming near the prison
- A Danish soldier and two Iraqis are killed after a truck carrying armed Iraqis was stopped during a routine patrol near Basra
- Two US soldiers are shot and wounded as they leave a restaurant in the capital, Baghdad, on Saturday
- The Iraqi police chief of northern city of Mosul is wounded and two officers killed in an ambush
- Sabotage is suspected in a fire at a sewage treatment plant in the south
The damaged oil pipeline links the giant oilfields at Kirkuk, which is responsible for 40% of Iraq's production, with a Turkish terminal at Ceyhan.
It had only just opened on Wednesday for the first time since the invasion of Iraq in March, when the fire broke out on Friday at a section in Baiji, north of Tikrit - hometown of ousted President Saddam Hussein.
The water pipeline breach flooded a main Baghdad underpass
The US-appointed interim oil minister in Iraq, Thamir Ghadban, said he believed an explosive device caused the blast.
Firefighters were struggling to bring the blaze under control when a second blast sparked a new conflagration near the first one.
An Iraqi geologist on the scene told the Reuters news agency he believed the second blast, too, was sabotage.
Oil exports are key to US plans for reconstructing Iraq, and engineers have worked for months to get pipelines - crumbling after more than a decade of UN economic sanctions - up and running again.
A US army spokeswoman said: "The North Oil Company is on site to make repairs, which are estimated to take at least two weeks to one month."
Mr Ghadban admitted there was a problem with security in Iraq, although he stopped short of criticising the US-led administration.
"In the past regime, we had the oil police, the army and the co-operation of the tribes, as well as what we call internal security," he said in remarks quoted by AFP news agency.
"Now all this has disappeared. There is a void in security."
An international security company, Erinys, won a US contract to guard oil installations, Reuters reported on Sunday.
The company will reportedly hire 6,500 guards to protect oil infrastructure from sabotage.
In Baghdad, engineers warned it would take eight hours to repair the breached water pipeline that flooded main roads in the city.
The International Red Cross said some 300,000 residents were without water and warned of people's increasing impatience with the lack of reliable basic services.
Officials say the water pipeline was sabotaged, and local residents reported hearing an explosion in the morning and a car driving away from the area at speed.