Suyadi, a marine transportation officer in Tanjung Priok, North Jakarta, told The Jakarta Post he received a report at 6:45 am from a tugboat that its crew had seen a downed plane, suspected to be the Lion Air jet, at Tanjung Bungin in Karawang, West Java.

"At 7:15 am, the tugboat reported it had approached the site and that the crew had seen debris from a plane," Suyadi said.

A tanker and a cargo ship approached the area, he said, and a rescue boat from the agency was also on its way.

Debris, thought to be from the plane, including seats, was found near an offshore refining facility in the Java Sea, an official with state energy firm Pertamina said.

The plane was scheduled to land at Depati Amir Airport in Pangkal Pinang at 7:10 am.

There were two pilots and six flight attendants on board, the National Transportation Safety Commission said in a statement.

Sindu Rahayu, from the Indonesian Air Transportation Directorate General, said in a statement: "The directorate general is coordinating with the National Search and Rescue Agency, Lion Air, the Sea Transportation Directorate General and the Indonesian Flight Navigation Service Institution in search and rescue activities."

The aircraft was delivered to Lion Air in August. It was powered by two CFM LEAP-1B engines.

Flightradar24 tweeted that the plane was "brand new" and Lion Air received it only three months ago.

Australia told Indonesia that it had not received any emergency signals from the plane, rescue agency chief Syaugi said.

After the crash, the Australian government instructed its officials and contractors not to fly on Lion Air. It made the announcement on its website. The crash is Indonesia's worst air disaster since an Air-Asia flight from Surabaya to Singapore plunged into the sea in December 2014, killing all 162 on board.