Indonesia is to launch a "special audit" of Lion Air's operations in the wake of last week's deadly crash that killed 189 people, the government said on Monday.

The budget carrier has been a regular target of complaints about poor service, unreliable scheduling and safety issues, including a fatal 2004 crash.

That safety record has been under the microscope since a new Boeing 737 Max 8 plunged into the Java Sea just 12 minutes after taking off from Jakarta last Monday.

"We will conduct a special audit of the crews' qualifications and staff communication," transportation minister Budi Karya Sumadi told reporters on Monday.

"This is a preventative measure (the accident) is a very expensive lesson for us."

Civil aviation authorities in the United States and Europe were also being consulted for their help in the probe, he added.

Meanwhile, authorities have extended their search as they collect more body parts and shattered debris from the spot where the plane crashed during a routine one-hour flight from Jakarta to Pangkal Pinang.

Scores of body bags filled with remains have been collected and sent for DNA testing, but so far just 14 people have been identified.

Search and rescue agency head Muhammad Syaugi tearfully apologised on Monday as relatives' clamour for answers grew louder, with accusations that the pace of recovery is lagging.

"We are not perfect human beings," he said, sobbing.

"We have flaws, but we [are] doing the best we can."

The Lion Air investigation comes after Indonesia's government ordered an inspection of all Boeing 737 Max 8 planes in the country.

All were found to be airworthy although two required repairs for "minor" problems.

The ministry had previously removed several Lion Air executives and technicians, saying they were needed to help authorities in the investigation.

A week after the disaster, there is still no answer as to what caused the crash.

Divers have pulled the plane's flight data recorder from the water, but are still hunting for the cockpit voice recorder— a key device that could provide clues to what caused the almost brand-new plane to plunge into the sea.

Lion Air's admission that the doomed jet had a technical issue on a previous flight — and the captain's request to turn back to the airport minutes before its fatal dive — have raised questions about whether it had faults specific to one of the world's newest and most advanced commercial passenger planes.

But the accident has also resurrected concerns about Indonesia's poor air safety record, which until recently saw its carriers facing years-long bans from entering EU and US airspace.