Four Katyusha rockets on Thursday hit the heavily fortified Green Zone in Baghdad without causing casualties, according to the Iraqi military.

The attack took place after midnight when the four rockets landed in the Green Zone, which houses some of the main Iraqi government offices and the US embassy, the media office of the Iraqi Joint Operations command (JOC) said in a statement.

Later, the Iraqi forces found a rocket launcher in an area near the site of the former military al-Rashid Camp in southeastern Baghdad, Xinhua news agency quoted the statement as saying.

No group has so far claimed responsibility for the attack.

On Saturday, two Katyusha rockets hit a military base, housing US forces, near the Iraqi capital Baghdad without casualties.

Last month, the Iraqi military had confirmed that two rockets hit a military base housing international coalition forces near Baghdad.

In January, the attack at the Baghdad International Airport also killed Abu Mahdi al-Muhandis, the deputy commander of Iran-backed militias known as the Popular Mobilisation Forces (PMF).

The Iranian attack came after a US drone attacked on January 3 a convoy at Baghdad International Airport that killed Qassem Soleimani, commander of the Quds Force of Iran’s Islamic Revolution Guards Corps, and Abu Mahdi al-Muhandis, deputy chief of Iraq’s paramilitary Hashd Shaabi forces.

More than 5,000 US troops have been deployed in Iraq to support the Iraqi forces in the battles against Islamic State militants.