A search for the plane and its passengers was called off late on Saturday (local time) because it was too dark and the water too deep for craft available, police said.
Jesse Robredo was on his way to his hometown in the central Camarines Sur province from Cebu when the propeller-driven Cessna plane he was on malfunctioned and the pilots decided to land at the nearest air field on Masbate island.
Robredo, 54, is an ally of President Benigno Aquino.
Witnesses saw the plane plunging into the water, about 500 metres from the runway. Robredo's police escort was rescued by fishermen and brought to a nearby hospital with minor injuries.
"They were not able to make it to the airport," Colonel Generoso Bolina, an army spokesman told reporters, saying they immediately sent search and rescue teams but could not find any wreckage.
Local television said Robredo was on the phone with his wife hours before the plane went down, saying the propeller had stopped working.
