The co-pilot who deliberately crashed the Germanwings plane in the French Alps rehearsed his actions on an earlier flight in the same aircraft on the day of the disaster, an interim accident report has indicated.

In the fatal crash on March 24, co-pilot Andreas Lubitz, 27, had selected just 100ft (30m) as the altitude after the captain left the cockpit of the Airbus A320, the report by French air accident bureau BEA said.

"Several altitude selections towards 100ft were recorded during descent on the flight that preceded the accident flight, while the co-pilot was alone in the cockpit," the BEA added.

Other altitudes, including 49,000ft (14,935m) and 21,000ft (6,400m), were also selected although the plane actually descended very little during the four-and-a-half minutes the captain was away on the earlier Dusseldorf-Barcelona flight, a graph in the interim report showed.

Later on the morning of March 24, Lubitz and his 34-year-old captain had flown the return leg on the Airbus A320 from Barcelona to Dusseldorf.

Cockpit voice recorder evidence has shown Lubitz locked the captain out of the cockpit and put the Airbus A320 into a continual descent, with the plane crashing into a mountain with the loss of all 150 people on board, including three Britons.

There have been various reports about Lubitz's mental state and his fitness to fly. On this, and other matters related to the fatal crash, the BEA said today:

:: During Lubitz's training and recurrent checks, his professional level was judged to be above standard.

:: In April 2009 his Class 1 medical certificate was not revalidated by the aeromedical centre of Lufthansa, Germanwings' parent company, due to depression and the taking of medication to treat it.

:: In July 2009 Lubitz obtained a new certificate valid until April 9 2010 but it came with a notice of special conditions and restrictions. His pilot's licence then included a limitation which required the aeromedical examiner to contact the licence-issuing authority before proceeding with a medical evaluation relating to any extension or renewal of the medical certificate.

:: He had obtained annual Class 1 medical certificates with the special conditions and restrictions each year after that, with the last being issued in July 2014 and valid until August 14 2015.

:: His schedule showed he had not flown between March 13 and March 22 2015. On March 23, the day before the crash, he was on stand-by and had flown from Dusseldorf to Berlin-Tegel in the early hours before returning to Dusseldorf as a passenger.

:: The largest parts of the crashed plane were about 10ft-13ft (3m-4m) long. One of the engines was broken into many pieces.

Cockpit door security was strengthened on passenger planes after the 9/11 attacks in the US. Evidence has shown that the captain in the Germanwings disaster tried to break down the cockpit door after being locked out.

Today, the BEA said its main focus was on "the current balance between medical confidentiality and flight safety" and the "compromises" made on security after 9/11, notably on cockpit-door locking systems.

One of the Britons killed was Paul Bramley, 28, who was originally from Hull. He was studying hospitality and hotel management at Cesar Ritz College in Lucerne and was about to start an internship.

Another of the Britons who died was father-of-two Martyn Matthews, 50, a senior quality manager from Wolverhampton.

Also killed was seven-month-old Julian Pracz-Bandres, from Manchester, who died alongside his mother, Spanish-born Marina Bandres Lopez-Belio.