A power cut halted operations at Saudi Arabia's PetroRabigh refining and petrochemicals complex, the company said late on Saturday.
The joint venture, owned by Saudi Aramco and Japan's Sumitomo Chemical, said in a bourse statement that supplies of power and steam had been interrupted from provider Rabigh Arabian Water and Electricity Co (RAWEC) on Saturday.
The company said it was working on bringing back production units at the giant petrochemical complex, which includes a 400,000 barrel per day oil refinery.
On Sunday morning, company officials were not available to comment and it was not clear whether power supplies and production had resumed to any degree.
RAWEC is owned by Japan's Marubeni, JGC Corp, Itochu, Saudi Acwa Power and PetroRabigh.
PetroRabigh can produce an annual 18 million tonnes of refined products and 2.4 million tonnes of petrochemicals in the first phase of the project.
In May, Saudi Aramco and Sumitomo Chemical Co said they planned to go ahead with a $7 billion expansion of their complex in Rabigh, on the Red Sea coast. The Rabigh II project, now under construction, is to start operating in early 2016.