Related reading:

BAGHDAD, Nov. 24 (Xinhua) -- A suicide tanker truck bomb attack on Thursday killed some 80 Shiite pilgrims, including 24 Iranians, at a fuel station in Babil province in south of the Iraqi capital of Baghdad, security sources said.

The attack occurred in the afternoon when a suicide bomber detonated his explosive-laden tanker truck at a fuel station in the town of Shomali in east of the provincial capital city of Hillah, some 100 km south of Baghdad, destroying buses carrying Iranian pilgrims and many nearby vehicles.

The pilgrims were returning home after observing a major ritual of Arbaeen in the Shiite holy city of Karbala, some 110 km south of Baghdad.

The Shiite Muslims had already observed the death day of Imam Hussein, one of the Shiites' twelve most revered Imams killed in 680 A.D. and buried in Karbala, on Oct. 12, in a ritual named Ashura Day, but they usually continue their mourning until the ritual of al-Arbaeen, or 40 days after the Imam's death, which took place on Nov. 21.

The massive blast killed and wounded more than 100 people, but the security officials gave conflicted reports about the exact number of casualty. However, the Iraqi NINA news agency quoted Falah Radhi al-Khafaji, the head of the security committee of Babil's provincial council as saying that the massive blast killed 80 people and wounded 31.

Many of the casualties at the busy fuel station were Iranian and Pakistani nationals, NINA said.

For its part, Iran condemned the terrorist attack and confirmed the death of 24 Iranian pilgrims, according to official IRNA news agency.

"It is an indication of frustration," IRNA quoted Foreign Ministry Spokesman Bahram Qasemi as saying.

The terrorists launched such attacks to compensate for the repeated defeats they have suffered recently, Qasemi said.

"Such brutal and inhuman acts are not going to affect the determination of the Iraqi people and its government; neither could they disrupt the Islamic republic's joint fight with Iraq against terrorism," he said.

Later in the day, the Islamic State (IS) group claimed responsibility for the attack, saying that an Iraqi suicide bomber, named Abu Fahad, struck buses carrying Shiite pilgrims, including Iranians, at the Shomali fuel station and the nearby Anwar Babil restaurant near the highway, according to an online statement, of which the authenticity could not be independently verified.

The Iraqi President Fuad Masoum strongly condemned the attack that killed many civilians, most of who were women and elderly.

Masoum expressed his "deep sadness to the death and wound of Iraqi people, Iranian, Pakistan and Muslim pilgrims from other countries."

The United Nations Assistance Mission for Iraq (UNAMI), in a statement condemned in the strongest terms the terrorist truck bombing near the city of Hilla in the Babil province, saying that the IS extremist group is seeking to avenge their losses in the IS-held city of Mosul in northern Iraq.

"This cowardly suicide attack is deliberately aimed at exacting maximum casualties among civilians. Many of the victims were pilgrims returning from the Arbaeen commemoration in the City of Karbala," the statement quoted the UN envoy to Iraq and the UNAMI chief Jan Kubis as saying.

The bombing underscores the importance of the ongoing fight against IS militant group in Mosul, the capital of Nineveh province.

"The more Daesh (IS group) feels cornered on the frontlines, the more they may seek to avenge their losses with attacks against unarmed civilians," Kubis said.

Thursday's attack came as the Iraqi forces and allied paramilitary units, known as Hashd Shaabi, are surrounding the city of Mosul to drive out the IS militants from their last major stronghold in Iraq.

The IS terrorist group frequently carried out such suicide attacks against Shiite pilgrims who perform communal rituals in Iraq, in an attempt to provoke sectarian strife in the violence-shattered country.

Terrorist acts, violence and armed conflicts killed 1,792 Iraqis and wounded 1,358 others in October across Iraq, the United Nations Assistance Mission for Iraq said.

Many blame the current chronic instability, cycle of violence, and the emergence of extremist groups, such as the Islamic States, on the U.S., which invaded and occupied Iraq in March 2003.