Rescuers are searching for 38 people missing in rough seas after a ferry sank near Indonesia’s resort island of Bali.

Four people died and 29 have been rescued, according to the Surabaya Search and Rescue Agency.

The KMP Tunu Pratama Jaya sank almost half an hour after leaving East Java’s Ketapang port late Wednesday, the National Search and Rescue Agency said. It was bound for Bali’s Gilimanuk port 50km away.

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The ferry was carrying 53 passengers, 12 crew members and 22 vehicles, including 14 trucks, it said.

The ferry sinking was witnessed by the on-duty officer at the port before it was reported to the rescue team.

Many of those rescued were initially unconscious after drifting in choppy waters for hours, Banyuwangi police chief Rama Samtama Putra said.

Rescue cues on nine boats, including two tugboats and two inflatable boats, have been searching for the missing people, battling waves up to 2m high in the overnight darkness.

Ferry tragedies are common in Indonesia, an archipelago of more than 17,000 islands where ferries are often used as transport and safety regulation enforcement can be lax.

Family members came to the departure port in panic, some weeping, as they sought reassurance about their loved ones and hoped they were among the survivors.

Many of those rescued were unconscious after drifting in choppy waters for hours, Banyuwangi police chief Rama Samtama Putra said.

No Australians are believed to be involved in the accident at this stage.

“The Australian Government expresses its sincere condolences to those impacted by the ferry accident in the Bali Strait,” a Department of Foreign Affairs and Trade spokesperson said.

“The Consulate-General in Bali is receiving regular updates. We will continue to monitor the situation closely.”