The Philippines postponed on Sunday the removal of fuel from a tanker that sank in Manila Bay, with fears of an environmental catastrophe growing as leaking oil reached shore for the first time.

The siphoning of the 1.4 million litres of industrial fuel oil from the vessel's hold was pushed back to Tuesday at the earliest so divers could seal nine leaking valves first, Philippine Coast Guard spokesman Rear Admiral Armando Balilo told reporters.

The tanker sank in bad weather off Manila early Thursday, killing one crew member and leaving the country facing the possibility of its worst oil spill ever.

"An order was given to seal the valves first before the start of the siphoning operations in order to prevent further leakages," Balilo said Sunday.

"The weather remains bad out there but they have a target to finish this (sealing the valves) by tomorrow."

Balilo said leaking oil had now reached a patch of shoreline in Hagonoy municipality, around 40 kilometres (25 miles) northwest of Manila.

Coast guard cleanup teams were dispatched to the area Sunday to spray oil dispersants, he said.

Balilo had no estimates as to how much beach was affected or what kind of damage the oil had done.

The coast guard has warned that if the entire cargo were to leak, it would be an "environmental catastrophe".

It has also called for a suspension of fishing in Manila Bay to prevent people "eating contaminated fish".

The Philippines has struggled to contain serious oil spills in the past.

It took months to clean up after a tanker carrying 800,000 litres of industrial fuel oil sank off the central island of Mindoro last year, contaminating its waters and beaches and devastating the fishing and tourism industries.

Another tanker sank off the central island of Guimaras in 2006, spilling tens of thousands of gallons of oil that destroyed a marine reserve, ruined local fishing grounds and covered stretches of coastline in black sludge

Meanwhile, another coast guard team was dispatched to the mouth of Manila Bay on Saturday to join the search for an unspecified number of crew members who were aboard a second tanker that sank nearby, Balilo said Sunday.

The wreck of the MTKR Jason Bradley has been located and a salvage will follow, a coast guard statement said, adding it had no cargo on board.

The sinkings occurred as heavy rains fuelled by Typhoon Gaemi and the seasonal monsoon lashed Manila and surrounding regions in recent days.