Fuel costs will tick up between 17 and 24 pesos (29 to 40 US cents) per litre this week, Energy Secretary Sharon Garin told a congressional committee on Monday, as oil prices soared on fears about supplies from the Middle East.

The expected increase, which was not broken down by specific product, will be spread out over several days, she said.

"Some companies have volunteered not to impose the increase in one day. They're staggered over three days or five days, depending on the company," Garin explained in a televised interview.

"We have to remember these are not regulated prices. They just have to inform us what the increases are and justify it," she said.

At a petrol station in Metro Manila, AFP journalists saw motorcycles, taxis and private cars queuing in scorching heat.

Gas station attendant Enrico Guda, 31, said the normal number of vehicles the station handled in a day had doubled to about 1,000 as customers sought to fuel up before prices jumped.

"The line started 24 hours ago. Morning, afternoon, even at dawn," he said.

Francis Aranda, a 25-year-old university student, told AFP the spike "hurts".

"I'm planning to use half my (weekly) fuel allowance so I won't have to worry in the coming days in case the war in Iran continues," he said.

Police, meanwhile, have been instructed "to inspect gasoline stations in their localities... and gather evidence of profiteering or hoarding", Philippine National Police spokesman Brigadier General Randulf Tuano told a news briefing Monday.

The ferries that tens of thousands rely on each day to traverse the archipelago nation of 116 million were also in the process of hiking fares.

Starlite Ferries, a relatively small operator in the central Philippines, announced that a 25 percent increase would take effect Tuesday for both passengers and cargo.

Montenegro Shipping Lines, which operates a fleet of 48 vessels, said its prices would go up 10-20 percent from March 23.

President Ferdinand Marcos last week cited the rocketing price of fuel in announcing a shift to a four-day work week for non-essential government employees while ordering agencies to cut their fuel and power consumption by 10-20 percent.

He also called on Congress to authorise him to reduce excise taxes on petroleum products if the price of crude oil breached $80 per barrel, a request an administration spokeswoman said Marcos would formalise on Monday.

West Texas Intermediate, the main US oil benchmark, and Brent crude prices both sit north of $110 a barrel.