Germanwings pilot Andreas Lubitz was recommended for psychiatric treatment weeks before crash

Investigators probing the Germanwings air crash have called for new world rules requiring medical professionals to warn authorities when a pilot's mental health could threaten public safety.

Flight 9525 from Barcelona to Dusseldorf crashed in the French Alps on March 24 last year, killing 150 people including three Britons.

An earlier report found evidence suggesting co-pilot Andreas Lubitz, who had previously been treated for depression, deliberately downed the plane after locking the pilot out of the cockpit.

French air accident bureau BEA has now published its final report on the crash, urging new rules on medical reporting about pilots.

The Britons killed were Paul Bramley, a 28-year-old from Hull who was studying hospitality and hotel management at Cesar Ritz College in Lucerne and was about to start an internship, Martyn Matthews, a 50-year-old father-of-two from Wolverhampton who worked as a senior quality manager, and seven-month-old Julian Pracz-Bandres, from Manchester who had been travelling with his mother, Spanish-born Marina Bandres Lopez-Belio, 37.

The report, delivered by experts on Sunday almost one year after the crash, also found that a doctor had referred Lubitz to a psychiatric clinic a fortnight before the crash.

It said a number of doctors who treated the 27-year-old in the weeks before the crash did not inform authorities about concerns around his mental health.

Families of the victims had previously been told Lubitz had seen 41 doctors in recent years but under German law none was able to alert his employers to his state of mind.

The BEA said because Lubitz had not informed anyone about the doctors' warnings, "no action could have been taken by the authorities or his employer to prevent him from flying."

Arnaud Desjardin, who led the investigation, said at a press briefing as the report was delivered, experts found the co-pilot's symptoms at that time "could be compatible with a psychotic episode", but this information had not been communicated to Germanwings.