Madrid - Spanair has instructed pilots to increase checks on takeoff warning systems of MD planes after the August 20 crash at Madrid airport that killed 154 people, press reports said Wednesday.

A commission investigating the accident has found that the wing flaps of the MD-82 which crashed were not correctly deployed, according to a preliminary draft report leaked to the media. Spanair confirmed that it had received a copy of the report.

The flaps are moveable panels on the rear edge of a plane's wings that help lift it on take-off.

The take-off warning system that should have alerted the pilots about the problem did not sound, the report was quoted as saying.

The same problem occurred on an MD-82 that crashed in Detroit in 1987, also killing 154 people.

The plane maker McDonnell Douglas subsequently advised pilots to check the take-off warning mechanism before every flight, but Spanair instructions only included checks before the first flight of the day and when the crew changed.

Spanair did not exist when McDonnell Douglas issued the recommendation, which it had not been informed of, operational director Javier Muela was quoted as saying.

The plane that crashed began its journey in Barcelona, but Muela said it was not certain whether the pilots checked the warning system during a stopover in Madrid.

He denied that a failure to do so could have caused the accident.

Spanair has, however, revised its handbooks to include checks of the warning mechanism before every flight, Muela said.

The MD-82 jet, which was heading for Las Palmas in the Canary Islands, crashed near the runway shortly after take-off.

Several pilots, meanwhile, stepped down from the investigating commission in protest at the leaking of the draft of the preliminary report to the press, according to the daily El Pais.

A second funeral mass for the victims was scheduled to be held Wednesday evening in Las Palmas, the capital of the Canary Islands, from where many of the victims came from.

The mass, which was to be attended by Crown Prince Felipe and Prime Minister Jose Luis Rodriguez Zapatero, followed a bigger one in Madrid last week. dpa