MANILA, Philippines ? (UPDATE) Barely a week after their last price increase, local oil companies have again raised prices of gasoline by 50 centavos a liter, and of diesel and kerosene by 25 centavos a liter.

Petron Corp., Chevron Philippines, Seaoil Philippines, Phoenix Petroleum Philippines, Eastern Petroleum, and Unioil Petroleum Philippines Inc. made their respective price adjustments 6 a.m. on Tuesday.

The oil companies said the latest price increase reflected the upward trend of global petroleum prices. Last March 3, the oil companies already raised prices of gasoline by P1 a liter, and of diesel and kerosene by 75 centavos a liter.

Data from the Department of Energy showed that the price of the regional benchmark Dubai crude rose to $77 a barrel as of March 9, from the $73-a-barrel average in February.

Prices of unleaded gasoline based on the Mean of Platts Singapore benchmark for refined petroleum products, also rose to $ 91 a barrel in the first nine days of the month, from the previous month's average of $87 a barrel.

Similarly, MOPS-based diesel prices increased to $87 a barrel within the Mar. 1-9 period, compared to the $84-a-barrel average in February.

According to the DoE oil monitor report, the high oil prices in the global market were predominantly bolstered by supply worries owing to a strike at French energy major Total and tensions between crude-exporter Iran and the West over Tehran's nuclear weapons ambitions.

The DoE cited analysts as saying that these factors, however, can only temporarily support the oil price for as long as the underlying fundamental (supply and demand) data remained weak.

"It has been proven during the past several months that prices moving beyond $80 a barrel were only short-lived. It would be difficult to support oil above the $80-a-barrel level because supply still outstripped demand," the report stated.