Oman Oil Refineries and Petroleum Industries Co (Orpic) plans scheduled maintenance at some refinery units from June 25 for about a month, the operator said on Thursday.

"Production of fuel products and chemicals will continue, but at a lower level. The shutdown will take around a month," Orpic said in a statement emailed to Reuters.

"Orpic has ensured that the supply to the market will not be interrupted. Continuity of supply has been ensured through to the consumer."

Orpic operates two refineries: Sohar with a total processing capacity of 116,000 barrels per day (bpd) of Omani crude and Mina al-Fahal with a refining capacity of 106,000 bpd.

The company declined to say which refinery or units will be affected by the shutdown.

The Sohar refinery resumed normal operations last month after repair work forced a shutdown in April.

Oman's oil ministry has sold 4 million barrels of July-loading Oman to Royal Dutch Shell due to the shutdown, traders said.

The excess supply coupled with weak crude demand in Asia have lowered DME Oman's premium to Dubai quotes to about $1 per barrel this week, down from $1.60 in the same period last month, Reuters data showed.

Oman pumps around 950,000 bpd of crude and aims to maintain this level for the next two to three years. – Reuters