At least 20 people, mostly children, have drowned and scores are missing after an Australia-bound boat carrying Middle Eastern asylum-seekers sank off Indonesia, police said Friday.

Twenty-five people were plucked to safety but about another 75 were unaccounted for after the boat, carrying people from Lebanon, Jordan and Yemen, went down off the main island of Java, police said.

It came just days ahead of new Australian Prime Minister Tony Abbott's visit to Indonesia, his first overseas trip since winning power this month, for talks that will focus on his hardline policies aimed at stemming the flow of asylum seekers.

Boatpeople were a key battleground in the Australian elections due to growing public anger as thousands continue to arrive after making the hazardous sea crossing from Indonesia.

Warsono, a police official in Cianjur district on Java, said that local people found the asylum seekers' bodies floating in an estuary on Friday morning.

"Local people found 20 dead bodies floating in the water, most of them are children," he said. "The number of deaths may increase."

"Local people said their boat had broken into several pieces," he added, although he did not know when the accident happened.

The official, who like many Indonesians goes by one name, added that the boat was believed to have been carrying 120 people when it went down.

He said they were asylum-seekers heading to the Australian territory of Christmas Island.

They had departed from the fishing town of Pelabuhan Ratu in the district of Sukabumi on the south coast of western Java, he said.

Hundreds of asylum-seekers from around the world have died in recent years trying to make the treacherous sea crossing from Indonesia to Australia on rickety, wooden boats.

They normally pay people-smugglers huge sums to make the crossings, and almost always head for Christmas Island, which is far closer to Indonesia than it is to the Australian mainland.

Abbott will begin a two-day visit to Indonesia on Monday, with talks expected to focus on his tough boatpeople policies that have caused anger in Indonesia.

He has ordered a military-led border protection plan to deter boatpeople which will see vessels turned back when it is safe to do so.

On Friday, he described asylum-seekers arriving by boat from Indonesia as a "passing irritant" to the countries' relationship and denied the plan would jeopardize relations with Australia's northern neighbor. (AFP)