A basic pilot error may have caused the Spanair plane crash at Madrid airport which killed 154 people, it has emerged.

The crew of the MD-82 aircraft failed to extend the wing flaps which are vital for take-off and then an automatic alarm system - designed to alert them to the mistake  - failed because of a supposed electrical fault.

The new theory was reported in the Times, the American Wall Street Journal and Spanish newspaper El Mundo after 'media leaks'  from the Madrid investigation.

Disaster: The charred tail of the crashed Spanair plane which may have been caused by a 'basic' pilot error

Just 18 people survived after the packed jet bound for the Canary Islands crashed into a ravine at the side of the runway moments after take-off on August 20.

The findings are said to be from preliminary data take from the 'black box' flight recorders on the plane.

The information, on the recorders sent to the Aircraft Research Establishment at Farnborough for examination, showed its two engines worked as normal up to the crash but the flaps on the wing's trailing edge and slats on the leading edge - crucial for taking off -  were not set.

They are on a list of 'killer items' pilots triple check before take-off.

The cockpit voice recorder, which was recovered from the crash, showed the crew had said  'Flaps OK, Slats OK' while reading their check list.

A loud alert system should have warned them of the problem as soon as they applied take-off power but it did not work.

Airliners were installed with these warning devices decades ago because so many accidents were caused by pilots failing to set the flaps.

Two other alarms that warn of nearby ground and imminent stall were also said not to have worked in the Spanair plane as the pilots lost control of it.

The alarm's failure could be down to a technical fault or it being switched off.

The ill-fated flight had been due to take-off earlier in the day but after moving away from the terminal and approaching the runway, it returned because of a problem with a temperature gauge.

It is possible this was part of a broader electrical problem, according to experts.

Spanish officials called the leaks incomplete but did not deny them.

A previous theory was an engine on the jet may have rammed into reverse, causing the plane to veer off the runway and explode.

Both the pilot and co-pilot were killed in the disaster.