Taiwan's Formosa Petrochemical is reportedly planning to increase the operating rate at its 540,000 barrels-per-day (bpd) refinery in Mailiao.

The refinery, which is currently under maintenance period, will maintain the run rate lower than normal, reported Reuters.

A company spokesman said that the refinery is expected to have processing capacity of 480,000 to 500,000 bpd of crude in September which is lower than its normal capacity of 520,000 to 530,000 bpd.

The refinery is said to have processed 400,000 bpd of crude this month.

"Margins are not very good, so most of the (buyers) do not want to lift as much and we do not want to keep a high inventory," the spokesman said.

The company had already lowered operating rates in July and August following maintenance at its crude distillation unit, residual fluid catalytic cracker (RFCC) and a residue desulphuriser unit (RDS).

According to the news agency, the oversupply of refined oil products, especially in middle distillates, has led to decrease in complex refining margins by more than 30% in July from the previous month at Asian refineries.

The refining margins have dropped by a further 10% due to plunging prices of gasoline.