Four rockets hit the Al-Balad airbase north of the Iraqi capital on Saturday, the military said, as security sources told AFP a local contractor for a US company managing Iraq's F-16s was wounded.

The attack came hours after Iraqi security forces raided an Islamic State hideout in the plains of Tarmiyah, with clashes leaving five jihadists and two pro-government fighters dead, according to the Iraqi military.

F-16s at the Al-Balad airbase were backing the ongoing Tarmiyah operation against IS sleeper cells at the time of the rocket attack, two security sources told AFP. There was no immediate claim of responsibility and it was not clear whether the rocket attack was linked to the anti-IS operations. 

Al-Balad is around 60 kilometres (40 miles) north of Tarmiyah. A local army source told AFP that Katyusha-style rockets were fired at Al-Balad. 

One of the rockets hit a part of the base hosting employees of Sallyport, the US contractor charged with maintaining the F-16 aircraft purchased from the US in recent years, the security sources said. "An Iraqi contractor sustained moderate injuries," one of the sources said. 

Another rocket hit a runway, without disrupting the take-off and landing of aircraft, while a third hit nearby woodlands, the source said. Iraqi army units at Al-Balad responded to the rockets by firing artillery at a position 12 kilometres east of the airbase where they believed the attack originated, the source added. 

It is rare for Iraqi security forces to respond so quickly to such an incident. 

Dozens of rocket attacks and roadside bombs targeted Western military and diplomatic installations last year.

US and Iraqi officials have blamed the attacks on armed factions with close ties to Iran -- not IS.  Iraqi authorities have struggled to hold the perpetrators of rocket attacks to account, as some of the groups accused are integrated into the state security forces and wield significant influence.

The rocket attacks continued even as the US-led coalition, which helped Iraq declare defeat against IS in 2017, drew down its forces and consolidated bases.

Al-Balad, one of the bases from which the coalition withdrew, once held a small US Air Force contingent but now hosts Iraqi armed forces and the Sallyport contractors. 

The US-led coalition has roughly halved its forces over the last year, leaving around 3,500 troops.

They are now based in Baghdad near the US embassy, as well as Ain al-Assad in the country's west and Arbil, the capital of the northern Kurdistan region.