An explosion along an oil pipeline extending from the northern Kirkuk oilfields to Bayji refineries caused damage to both the line and another parallel pipeline between Iraq and Turkey, on Tuesday.
Twenty-six people including three militants were killed and 59 wounded in separate attacks and military operations across Iraq, according to local authorities.
The ensuing fire hit only a section of the Kirkuk-Bayji pipeline which runs over the River Tigris, but caused a huge oil leak and dense black smoke in the area.
Firefighters were struggling to contain the damage, a source in the local oil industry said. The explosion is expected to halt production at Bayji refineries, which supply more than half of Iraq's oil products.
According to a source in the water department in Salahaddin, the explosion caused oil to seep into the Tigris river damaging water stations and triggering their temporary closure.
The water supply up to 100 kilometres south of the explosion site was affected due to the unimpeded oil flow, the source added. Water used for irrigation purposes was similarly contaminated.
In the aftermath of the attack, a series of fires were reported along the banks of the Tigris as a result of the leak, said a member of Salahaddin province's civil defence department.
Health officials in Tikrit and Bayji have reported several cases of suffocation as a result of smoke inhalation. The dark clouds of smoke mixed with gas are said to have gathered in the skies from Bayji to Tikrit, 40 kilometres south of the explosion site.
In another development, three car bombs exploded in central and eastern Baghdad, police said.
The first two bombs detonated in a parking lot near Baghdad's health ministry in the central district of Bab al-Muazzam. The attack was the most intense, killing 11 people and wounding 30.
Initial reports said seven people were killed and 23 wounded, but the dead and injured tolls were adjusted later.
The third car bomb exploded just minutes later in the eastern Zayouna neighbourhood, killing two people and wounding five.
In another attack in the Zaafaraniyah suburb, southern Baghdad, a blast near a police patrol killed a civilian and wounded two others.
In Baquba, 60 kilometres north of Baghdad, three Iraqi members of the same family were gunned down and two wounded in an armed attack on their vehicle, said the police.
In eastern Baquba, a civilian was killed and three members of the newly-formed Baquba Salvation Front were wounded in a mortar shell attack, the source of which was unknown.
The front, founded by the city's tribal leaders, was formed to fight al-Qaeda militants in the region.
Two people were injured in another round of shelling on a residential area, security sources in Baquba said. Police sources said they had also arrested nine wanted militants earlier Tuesday in Hashimiya, western Baquba.
Iraqi security forces said two Iraqis were killed and 13 wounded when an explosive charge detonated in a local market and near the police station in Galulaa, north-eastern Iraq.
Meanwhile, gunfights between militants and police left three people dead and two injured in Tikrit, 170 kilometres north of the capital, the local police department said.
A blanket curfew was imposed in the hometown of former Iraqi dictator Saddam Hussein.
Separately, Iraqi troops and US forces captured a senior member of al-Qaeda in Iraq, two snipers and 15 suspected terrorists during raids in Baghdad's north, the US military said in a statement on Tuesday.
The captured militant was believed to be the second-in-command to Abu Ghazwan, the head of a terrorist network with suspected links to al-Qaeda that targets citizens and is reportedly responsible for murder, robberies and kidnappings.
The US military said the network was suspected of staging attacks from a local mosque, and to be financing car bomb attacks.
"The cell is further suspected of storing and supplying weapons such as surface-to-air missiles, mortar rounds, mortar launchers, and heavy machine-guns to be used in future terrorist attacks," according to the US statement.
US forces also captured a suspected Iraqi terrorist with links to the Iranian Quds Force faction, in an operation early Tuesday, the statement said.
The Quds Force faction is a special unit in Iran's Islamic Revolutionary Guards that the US has recently accused of funding and training Shiite death squads in Iraq.
The captured militant is suspected of involvement in smuggling foreign fighters into Iraq.
During operations in the Tigris River Valley, US forces also killed three militants and detained 13 suspected terrorists earlier in the day.
Iraq's health ministry confirmed Tuesday cholera-related figures released earlier by the World Health Organization (WHO) according to which up to 16,000 people were suffering from acute watery diarrhea, the ministry confirmed during a press conference.
However, senior ministry officials told reporters that not all of them are confirmed cholera cases. Ten people have died so far in the in the Sulaymaniyah and Kirkuk provinces, according to the ministry and WHO.
Contaminated water sources have been blamed for the incidence of cholera - a waterborne disease which starts with acute diarrhea and can lead to death in just a few hours from severe dehydration and kidney failure.
On a different note, around 1.2 million children returned to classrooms in the autonomous Kurdish region at the start of the new school year on Tuesday.
Regional Vice President Omar Fatah told reporters this school year was different as the education system had been overhauled and improved, and promised the new methods would encourage students to pursue their education and assured "that their efforts will not be wasted." dpa str zh pa pb
