ISIS fighters march in formation (file)
ISIS fighters march in formation (file)Reuters

Officials in Iraq said Thursday at least 12 soldiers have been killed and more than 10 wounded in an attack on a military base outside the northern city of Mosul.

According to an Associated Press report, the attack began when a suicide bomber detonated an explosives-laden truck. Gunmen then opened fire, according to the report, which quotes army and police. Eight guerrillas were killed in the ensuing gun battle.

Guerrillas also blew up two oil and gas pipelines in the northern Saladin province, a security official said. "Militants detonated an explosive device near an oil pipeline and another near a gas pipeline in the town of Biji," Saladin Police Captain Omar al-Juburi told Anadolu Agency.

The explosions left thick black smoke in the air and oil spilling into the Tigris River, al-Juburi added. Local water authorities had to cut off water supplies to the area's purification plants.

A report on Xinhua claims that 15 people were killed in separate attacks by guerrillas in the nearby Nineveh province on Wednesday, when dozens of gunmen attacked an army base in the al-Mahallabiyah area.

The attackers came in more than 20 vehicles and a fierce clash took place with soldiers for three hours, a military source said. The battle left 13 killed, including five soldiers. Five others were also injured, the source added.

In a separate incident, a soldier was killed and another wounded when a roadside bomb struck the army patrol in Mosul.

Mosul has seen a series of attacks in recent months blamed on Al-Qaeda-linked Sunni militants.

Iraq is preparing to hold elections April 30, in which Prime Minister Nuri al-Maliki is seeking a third consecutive term.