Madrid- The credibility of a commission investigating the August 20 plane crash that killed 154 people in Madrid was questioned Friday after the main pilots' representative Valentin Villarroel resigned from it over leaks to the press.

Two other pilots had left the commission earlier. Infrastructure Minister Magdalena Alvarez said she would not accept Villarroel's resignation as long as the pilots' association APCC did not propose a substitute for him.

The pilots' association Copac had accused the ministry of leaking to the press a preliminary report of the commission, revealing that the Spanair MD-82 jetliner's wing flaps were not properly extended and that the plane's take-off warning system failed to alert the pilots of the problem.

It has also been revealed that the co-pilot was in charge of the plane.

On Thursday, the daily El Pais released a video of the accident captured by airport security cameras, showing the plane skid on the runway, crash just after take-off and explode in a ball of fire.

"There has been an accident, we have seen fire and smoke," an anxious woman's voice is heard saying in the control tower.

The commission will make the report public officially next week, sources close to the investigation said.

However, Villarroel's departure might reduce the report's judicial value, the sources added.

The airline Spanair has said that it has presented clarifications and corrections to the report.

The opposition conservative People's Party (PP) has asked the government to dissolve the commission, arguing that it was no longer credible, and to start the investigation from zero. (dpa)