JAKARTA: A boat carrying dozens of asylum seekers sank off the coast of Indonesia's main island of Java on Friday, killing at least 21 people, an official said.

Twenty-five people were rescued and transported to the Sukabumi immigration office for identification, said Cianjur police chief Lt Col Dedy Kusuma Bakti.

The search for survivors was continuing. Some survivors told officials that more than 100 asylum seekers from Lebanon, Pakistan and Iraq were believed to be aboard the boat, but the exact number of passengers was not known, Bakti said.

Survivors said the boat was headed for Australia's Christmas Island.

Lebanon's official National News Agency said 17 Lebanese drowned in the incident. Nine members of a single family were among the Lebanese victims, with a woman and her eight children dying and her husband surviving, the agency reported.

The incident came ahead of new Australian Prime Minister Tony Abbott's first visit to Indonesia next week. He is expected to meet with Indonesian President Susilo Bambang Yudhoyono.

Indonesia has said that the Australian navy's plan to intercept and force back Indonesian fishing boats crowded with asylum seekers could breach Indonesian sovereignty.

Scores of people from war-torn countries use Indonesia as a transit point every year, boarding rickety fishing boats bound for Christmas Island, located 500 kilometres south of Indonesia's capital, Jakarta.