Jakarta, Indonesia (CNN) -- Six people were rescued in the waters off Indonesia early Thursday as authorities search for survivors of a boat that reportedly had engine trouble a day earlier, Australian officials said.
Rescue workers searched all day Wednesday after the Australian Maritime Safety Authority received a call from someone who said they were on board a vessel having engine trouble with about 150 others, presumed to be asylum seekers.
The Australians said they were able to determine from the conversation that the vessel was about 8 nautical miles southwest of the island of Java. They alerted the Indonesian search and rescue agency, BASARNAS, which dispatched two helicopters and a rescue boat, BASARNAS spokesman Gagah Prakoso said.
Rescue workers were unable to find any signs of the vessel after searching a large area in the Sunda Strait between Java and the island of Sumatra, he said.
Later Wednesday, Australian search and rescue authorities said they updated the vessel's likely position based on drift modeling and tasked the container ship APL Bahrain to head to the area.
Early Thursday, the APL Bahrain reported seeing people in the water and managed to pick up six survivors about 42 nautical miles west of Java, Australian authorities said.
Two other merchant vessels were also at the scene Thursday morning, Australian authorities said. Two Australian defense aircraft, an Australian naval vessel, and two Indonesian search vessels were also expected to head to the area.
Several ships carrying people seeking asylum in Australia have run into trouble in the waters between Indonesia and Australia in the past two years. The issue has become a highly sensitive political topic in Australia.
The vessels often head for Christmas Island, a remote Australian territory closer to Java than to the Australian mainland.
Dozens of people are believed to have died after two ships capsized near Christmas Island in June. More than 200 people were rescued from those accidents.
CNN's Kathy Quiano in Jakarta and Jethro Mullen in Hong Kong contributed to this report.