BAGHDAD - Three Katyusha rockets on Monday landed near the US embassy in the heavily fortified Green Zone in central Baghdad, an Interior Ministry official said.

The attack took place around midnight when the three rockets landed near the US embassy in the Green Zone, which also houses some of the main Iraqi government offices, the official told Xinhua on condition of anonymity.

There were no immediate reports about casualties, the source said.

The heavily fortified Green Zone has been frequently targeted by insurgents' mortar and rocket attacks. The roughly 10 square km zone is located on the west bank of the Tigris River, which bisects the Iraqi capital.

Earlier in the month, the Iraqi Iranian-backed Shiite militia, known as Asa'ib Ahl al-Haq, led by Qais al-Khazali said that the Iranian initial response to the killing of Iranian military leader is done, and it is time for Iraq to respond to the US airstrike.

Al-Khazali's threat came after Iran fired ballistic missiles on Jan 8 on military bases housing US troops in Iraq's western province of Anbar and near the city of Erbil, the capital of the semi-autonomous region of Kurdistan.

On Jan 3, a US drone attacked a convoy at Baghdad International Airport, killing 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.