Rockets landed near a site managed by US oil company Halliburton and state-run businesses in Iraq’s southern city of Basra early on Monday, without causing damage or casualties, industry and police sources said.
Police said that three Katyusha rockets landed near the sites at the Burjesia residential and operations headquarters west of Basra at about 3am local time.
Officials from the state-run Basra Oil Company, that operates oil production in the south, said the attack did not affect production and export operations.
A rocket launcher and some unused rockets were found in a nearby farmland area, local police said.
Almost all foreign staff have left the country due to the global coronavirus pandemic and so the accommodation was largely empty.
No group has yet claimed responsibility for the attack and police said they sent additional forces to carry out a search operation in the area.
The attacks came as US forces withdrew from Al Taqaddum airbase and handed over operations to Iraqi forces at the weekend.
“The transfer of Taqaddum (Habbaniya) airbase is another step forward in the ongoing partnership between Iraqi Security Forces and the anti-ISIS international military Coalition,” Brig Gen Vincent Barker, the coalition's director of sustainment, said.
Over the last month, the coalition transferred four bases to the Iraqi security forces as it consolidates it resources into a smaller number of key locations.
"This wouldn’t be possible without the Iraqi security forces’ proven capability to bring the fight to ISIS," Brig Gen Barker said.
Coalition spokesman, Col Myles Caggins, said the withdrawal came "after months of planning".
At least 500 coalition troops left the air base, transferring $3.5 million (Dh12.8m) in property to the Iraqi government.
Col Caggins said that the Iraqi Ministry of Defence "remains strong against ISIS in Anbar Province".
Al Taqaddum airbase hosted US Marines plus Italian, Canadian and Spanish forces.
The withdrawal is a result of the victory over ISIS but also in response to repeated attacks by Iran-backed Iraqi militias that has pushed the US into changing footing in the country. The current coronavirus outbreak is also thought to be speeding up the process as it halts most training programmes for Iraqi soldiers.
Some Western troops are being pulled out of Iraq altogether and those who remain are being taken to larger centres.
Tensions between Washington and Tehran have increased during the last few months in Iraq after the killing of Iranian general Qassem Suleimani and Kataib Hezbollah founder Abu Mahdi Al Muhandis.
They were killed in a US operation in Baghdad in early January which triggered a series of tot-for-tat attacks between the two in Iraq.
Several US soldiers and contractors, as well as a British soldier, have died in attacks since the start of the year.