Maria Elena Bautista, transportation undersecretary, told reporters that the retrieval of 10 metric tonnes of endosulfan, a highly toxic fertiliser, and about one tonne of pesticides would take 12 to 16 days.

Bautista said about 250 tonnes of bunker fuel would then be removed before divers could get to the bodies.

The ferry ran aground and capsized at the height of typhoon Fengshen in June. Only 56 people are known to have survived the accident.

Salvage operations did not begin until August and authorities had to proceed cautiously to prevent the cargo from shifting and spilling.

"As of 1 p.m., (0500 GMT Tuesday), 22 packs of endosulfan, out of a total of 400, have been retrieved and contained in steel drums," Bautista said.

The retrieved packs, each weighing 25 kilos, were sealed in steel drums by members of US-based salvage firm Titan and local partner Harbor Star, after they were pulled out of the water.

The sinking of the MV Princess of the Stars is the country's worst sea accident since the Dona Paz ferry collided with an oil tanker in 1987, killing more than 4,000 people.

Ferries are a popular mode of transport for the masses in the Philippine archipelago because fares are cheap, but ageing vessels and overloading commonly cause accidents. (Reporting by Rosemarie Francisco; Editing by Valerie Lee)