The co-pilot who is believed to have deliberately crashed a Germanwings plane into the French Alps received psychiatric treatment for a “serious depressive episode” six years ago, German tabloid newspaper Bild is reporting.

One hundred and fifty people, including a Victorian woman and her adult son, died when the plane slammed into the mountainside on Tuesday.

• Who was Germanwings copilot Andreas Lubitz?
• Germanwings copilot crashed deliberately: prosecutor

A French prosecutor said the plane’s co-pilot, Andreas Lubitz, 28, deliberately crashed the Airbus A320, with the senior pilot locked out of the cockpit.

After listening to the cockpit voice recorders, prosecutors in France offered no motive for why Lubitz would take the controls of the plane, lock the captain out and deliberately set it to veer down from its cruising altitude at a speed of 3,000 feet per minute.

Citing internal documents and Lufthansa sources, Bild said Lubitz spent a total of one-and-a-half years in psychiatric treatment and that the relevant documents would be passed to French investigators once they had been examined by German authorities.

The chief of Lufthansa, which runs the low-cost Germanwings airline, Carsten Spohr told a news conference on Thursday that Lubitz had taken a break during his training six years ago, but did not explain why.

He said Lubitz passed all tests to be fit to fly.

“Six years ago there was a lengthy interruption in his training,” Mr Spohr said.

“After he was cleared again, he resumed training.

“He passed all the subsequent tests and checks with flying colours. His flying abilities were flawless.”

A Lufthansa spokeswoman said on Friday the airline would not comment on the state of health of the pilot.

Evidence seized from Lubitz’s homes but ‘no smoking gun’

The reports come as German police seized possessions, including a computer, from Lubitz’s homes.

German police search home of Andreas Lubitz. Photo: AFP

Officers combing through a flat kept by Lubitz in the western city of Dusseldorf said they had seized “various items and papers”, police spokesman Marcel Fiebig said.

“We will see whether this will explain what happened – everything is being examined,” he said, adding that there was no “smoking gun” to shed light on a possible motive.

Lubitz spent most of his time at his parents’ home in the small western town of Montabaur.

That upscale residence was also cordoned off by police and searched.

Men wearing gloves came out carrying briefcases, bags and boxes, an AFP journalist reported.

The city’s public prosecutor said in a written statement that searches in Duesseldorf and other places were aimed at “the discovery and securing of personal documents” to help clarify the situation.

Captain used axe in attempt to bash down door: report

The Bild newspaper also reported the captain who was locked out of the cockpit used an axe to try and force his way back in, citing security sources.

The cockpit flight recorder showed the captain repeatedly knocked and tried to get back in as the plane went into its fatal descent, French prosecutors said.

However, Bild reported that the captain also tried using an axe to break down the cockpit’s armoured door.

This could not be immediately confirmed, but a spokesman for Germanwings confirmed to news agency AFP that an axe was on board the aircraft.

Such a tool is “part of the safety equipment of an A320”, a spokesman said.

Federal Government, Qantas considering cockpit safety changes

The Federal Government and Qantas are considering changes to cockpit security following the crash.

Deputy Prime Minister Warren Truss said Australia’s aviation agencies were investigating if current cockpit safety requirements needed further strengthening.

“The current regulations do not require airlines to replace a pilot who temporarily leaves the cockpit,” he said.

“Careful consideration needs to be made following thorough investigation to ensure that altering current procedures does not open other potential vulnerabilities.”

“Our two major international and domestic airlines are undertaking their own safety and security risk assessments of cockpit procedures following the recent tragedy.”

A Qantas spokesman said the airline was “monitoring the information coming out of the French investigation” and was considering whether any changes to its existing safeguards were needed.

Strategic Aviation Solutions chairman Neil Hansford told ABC NewsRadio there had been several similar incidents in the past.

“We didn’t have these doors on cockpits to keep them sanitary before 9/11 so this is another flow-on effect,” he said.

Lufthansa chief sees ‘no need’ to change cockpit policy

Airlines including Norwegian Air Shuttle, Britain’s easyJet, Air Canada, Air New Zealand and Air Berlin all said they had introduced a requirement that two crew members must be in the cockpit at all times.

Regulations in the US already require that no pilot must ever be left alone at the controls and Canada has now followed suit.

Mr Spohr from Lufthansa said he believed such a policy change was unnecessary.

“I don’t see any need to change our procedures here,” he said.

“It was a one-off case. But we will look at it with the various experts at Lufthansa and the authorities. We shouldn’t lose ourselves in short-term measures.”