MANILA, Philippines -- As world oil prices hit new record highs almost every day, oil firms again raised prices of their fuel products -- this time by P1 a liter for gasoline, P2 a liter for diesel and kerosene and P1.50 a kilogram for liquefied petroleum gas -- over the weekend.

Initiating the price hike were Pilipinas Shell Petroleum Corp. and Eastern Petroleum Corp. at 12:01 a.m. Saturday, followed by Petron Corp., Chevron Philippines Inc., Total (Philippines) Corp., and Seaoil Philippines Inc. at 6 a.m.

Eastern and Total also increased the price of their auto LPG by P1 a liter.

The oil firms all cited skyrocketing world oil prices as the reason for this price adjustment, the 18th for the year.

According to data from the Department of Energy (DoE), the regional benchmark Dubai crude soared to a July average of $137.91 a barrel from $127.82 a barrel last month.

The price of unleaded gasoline based on the Mean of Platts Singapore (MOPS) benchmark for refined petroleum products surged to an average of $145.77 a barrel in the July 1-4 period from $140.30 a barrel in June.

MOPS-based diesel skyrocketed to an average of $177.05 a barrel in the first four months of the year from the June average of $169.36 a barrel.

After breaching the $900-per-metric-ton mark last month, the international contract price of LPG went further up this month to $936.50 per MT, $24 higher than the June price of $912.50 per MT.

The DoE, in its latest weekly oil monitor, said the rise in international oil prices could be attributed to a number of factors: tensions in Nigeria and the Middle East, talk that members of the Organization of Petroleum Exporting Countries want to reduce production, weather concerns, a weaker dollar, and the Fed?s inability to raise rates to contain inflation.

?(Apart from) the possibility of a supply cut from Libya, tension between Iran and Israel was also a concern. The ongoing rhetoric about possible attacks on Iran, the world?s fourth-largest oil producer and Opec?s second-largest exporter, left the market jittery,?? the DoE weekly monitor stated.

?If Israel or the United States launched an offensive attack, Tehran could try to halt shipments and seize control of the strategically important Strait of Hormuz, the Middle Eastern choke-point where about 40 percent of the world?s tanker traffic passes through,?? it added.

These possibilities led to market jitters, resulting in undue speculation.

Since the start of the year, gasoline, diesel, and kerosene prices had risen 18 times for a total of P18 a liter for gasoline and P19.50 a liter for diesel and kerosene.

This price adjustment brought prices of premium unleaded gasoline to between P59.75 and P61.98 a liter, diesel to between P53 and P54.97, and kerosene to between P57.10 and P60.30 a liter, inclusive of the 12-percent value-added tax.

LPG now costs between P631.50 and P688 per 11-kilogram cylinder.