The first blast occurred overnight near Beiji, 155 miles north of Baghdad, according to Colonel Sarhat Qadir of the Kirkuk police. Oil Ministry spokesman Assem Jihad said that the attack would not affect exports from the northern oil fields but said the blast cut supplies to the Beiji electric power station, forcing a reduction of 400 megawatts. Iraq produces a total of 4,000 megawatts of power.

Iraqi civil defence corps chief Anwar Amin confirmed the second explosion. 'A bomb placed 80 kilometres (50 miles) west of Kirkuk exploded at 8.20 am (0420 GMT) on the main pipeline to the Ceyhan terminal,' he said.

The pipeline was still ablaze Wednesday afternoon, said the fire chief for the Northern Oil Company, Jumaa Ahmad.

Cuts in the country now last more than 16 hours a day, making it difficult to cope with soaring heat which is already topping 100 degrees Fahrenheit.

The US-led coalition had made its ability to guarantee adequate electricity supplies a benchmark of success in restoring normalcy to Iraq but power cuts regularly last over 16 hours each day, made worse by soaring temperatures. Sabotage and a decaying infrastructure impede efforts to restore normality to electricity supplies.

Coalition officials fear that insurgents may step up attacks on infrastructure targets in the run-up to the 30 June transfer of sovereignty to undermine public confidence both in the US occupation authority and the new regime.

Iraq exports some 1.65 million barrels per day from the south and another 200,000 barrels per day from the north through Turkey.

A main export pipeline to the south in the Faw peninsula was set on fire in May 2004 which stopped crude oil flowing through one of the lines to the key export terminal of Basra. Iraq was to reduce exports to 1.1 million barrels a day from the south.