Early investigations into the latest Qantas incident have found no evidence suggesting a mobile phone or laptop computer caused the plane’s uncontrolled descent above Western Australia, officials say.

More than 70 people on Qantas flight QF72 from Singapore to Perth were injured when the Airbus A330-300, carrying 303 passengers and 10 crew, suddenly dropped altitude on Tuesday, hurling people around the cabin and forcing the pilot to make an emergency landing at Learmonth.

WA police earlier said at least 20 passengers and crew were seriously injured – some with spinal injuries and others with broken bones and lacerations.

The Australian Transport Safety Bureau (ATSB) says that while it is considering the possibility of electronic interference, it does not believe it was the cause.

“There is no evidence, at this stage, to indicate that the use of portable electronic devices by passengers contributed to the event,” the bureau’s investigation director Julian Walsh told reporters in Canberra today.

Mr Walsh said questions about this possibility would be included in a survey of passengers that will form part of the investigation.

“The investigation will be examining a broad range of factors that influence the operation of the aircraft,” he added.

Seven bureau staff remain with the jet at the Learmonth airstrip, near Exmouth on the West Australian coast.

Qantas, Airbus and French aviation body Bureau d’Enquetes et d’Analyses are all helping the ATSB in the investigation.

Mr Walsh said neither the ATSB nor Airbus was aware of a similar event involving the A330-300.

He went on to praise the work of the aircrew who immediately moved to isolate the vital cockpit voice recorder (CVR).

“The aircraft’s crew acted both promptly and responsibly to preserve the CVR data by ensuring that the CVR was isolated after the aircraft had been shut down.”

A preliminary ATSB report would be released in the next 30 days, Mr Walsh said, but if critical safety data was uncovered in the meantime it would be passed on to Airbus.

It is possible the jet may be flown to France where Airbus staff could remove components for further study.

“We have got at least another day’s work to do on the aircraft ourselves,” Mr Walsh said.

“Beyond that, that then becomes a matter for Qantas in terms of what they need to do to prepare the flight.”