Foreign diplomats and troops based across Iraq have been targeted in similar attacks more than two dozen times since late October, according to an AFP count.

Before dawn on Thursday, two rockets punched into an empty square near an Iraqi security headquarters in the Green Zone, the security forces said.

But an Iraqi security source told AFP the intended target appeared to be the US embassy, a sprawling compound a few hundred metres further south on the banks of the Tigris.

The Green Zone's sirens could be heard going off shortly afterwards.

There were no reports of casualties.

Earlier this month, two US military personnel and a British soldier were killed in a rocket attack on the Taji airbase further north, which was hit again two days later.

The 5,200 US troops stationed across Iraqi bases make up the bulk of the 7,500-strong coalition force deployed to help local forces beat back jihadist remnants.

Those troops are being drawn down this month, partly as an emergency response to the novel coronavirus pandemic and partly as a more permanent repositioning.

British, French, Australian and Czech forces who were in Iraq to coach Iraqi forces were being temporarily sent home as Baghdad had put a hold on training operations.

Trainers amount to a third of the total coalition troops.

But the coalition is also consolidating its forces into a smaller number of bases across Iraq and sending some troops out of the country in the process.

On Thursday, US-led coalition forces will hand over the northern air base of Qayyarah to Iraqi troops, the second such departure this month.