Iraq's largest oil refinery has been shut down following death threats to tanker drivers, jeopardising supplies of electricity across northern Iraq.
The Baiji refinery produces millions of gallons a day
The threats followed a steep rise in the price of petrol earlier this month, ordered by the government.
The oil ministry said the shutdown at Baiji was costing $20m (£12m) a day.
The ministry said it hoped the refinery, which has been out of action since the weekend, would be back up and running within days.
Daily crude oil production: 2.07m barrels
Daily export: 1.25m barrels, leaving 0.82m for domestic consumption
Pre-war production peak (estimated): 2.5m barrels
Current production goal: 2.5m barrels (revised down from 2.8-3m in Feb 2005)
Source: Brookings Institute
"Efforts are being made to convince the drivers to return to work," a spokesman said.
The Baiji refinery normally produces 8.5m litres (2.2m gallons) of petrol per day, along with 7.5m litres of diesel.
Oil distribution has been further disrupted by storms that have prevented exports being shipped from the Basra terminal in the south, Reuters said.
Although billions of dollars have been spent on infrastructure since Saddam Hussein's regime was toppled, fuel and electricity production have not reached the levels maintained before the US-led invasion of Iraq.
Raid on house
Elsewhere in Iraq, about 12 Shia Muslims were killed by insurgents after apparently failing to heed warnings that they should move out of their homes in the mainly Sunni town of Latifiya, about 30km (20 miles) south of Baghdad, officials said.
The victims were reported to be members of the same extended family.
However there were differing reports of the incident and who was involved. "A number of gunmen broke into three houses in Latifiya at dawn on Thursday, took 12 males aged between 20 to 40 and put them into a minivan owned by one of the victims, and machine-gunned them," Iraqi Army Capt Ibrahim Abdullah told Associated Press.
The AFP news agency said 14 people were killed, some of them women.
Reuters said the killings took place inside a house, where intruders slit the throats of 11 men and women.
Threat to Sudan
Also on Thursday, a suicide bomber killed four police officers and wounded five at a checkpoint near the interior ministry in Baghdad, officials said.
Four policemen were killed by a bomb in Baghdad
The attacker was dressed in a police uniform and blew himself up as police cars were entering the ministry, a police source said.
Meanwhile, a web statement attributed to the militant group al-Qaeda in Iraq said it was holding five Sudanese hostages.
The group said it had "arrested five employees of the Sudanese embassy in Baghdad, including diplomats".
It said the Sudanese government had "48 hours to clearly announce it is breaking off diplomatic relations with the [Iraqi] government... Otherwise the government must assume responsibility for sacrificing its diplomats".
At the weekend Sudan said six of its nationals, including five embassy employees and a "friend", had been abducted in Iraq.
IRAQ'S OIL MAY 2003 - DECEMBER 2005
Estimated pre-war level of crude oil production: 2.5m barrels a day (peak).
Estimated pre-war level of crude oil export: 1.7m to 2.5m barrels a day.
Figures for September 2005 based on incomplete data and represent averages for approximately half the month.
All data as of 14 December 2005.