A rocket landed at the headquarters for several global major oil companies, including U.S. giant ExxonMobil, near Iraq's southern city of Basra early on Wednesday, wounding two Iraqi workers, police said.
The rocket hit the Burjesia residential and operations headquarters west of the city, they said. There was no immediate claim of responsibility for the attack.
A security source said Exxon was preparing to evacuate some 20 foreign staff immediately.
Other companies operating at the site include Royal Dutch Shell and Italian Eni SpA, oil officials said.
Police said the rocket was a short-range Katyusha missile that landed 100 metres from the section of the site used as a residence and operations centre by Exxon.
Burjesia is near the Zubair oilfield operated by Eni.
Exxon evacuated staff last month after the United States cited unspecified threats from Iran for a decision to take hundreds of diplomatic staff out of Iraq.
Exxon had begun returning staff to Iraq, however, before Wednesday's incident.