Investigators said Monday it was still too early to establish the chain of events that led to last week's Air France Concorde disaster.

``You have to understand that we are at the start of a difficult inquiry,'' Alain Monnier, head of the inquiry commission appointed by Transport Minister Jean-Claude Gayssot, said after a day-long meeting. He told reporters there were ``certainties or near certainties'' a tire had burst, that there was an intense fire and that there were problems with the landing gear and engines. Monnier's commission is assisting the official French Accident Investigation Bureau (BEA) in the technical probe into last Tuesday's crash, which killed all 109 people on board the supersonic airliner and four on the ground. The Concorde, streaming a trail of fire, plunged into a hotel near the town of Gonesse less than two minutes after taking off from Roissy-Charles de Gaulle airport for New York. The government grounded Air France's five remaining Concordes immediately after the crash just north of Paris. After the world's only other Concorde operator, British Airways, resumed its flights within 24 hours of the accident, the pressure is on the French state-controlled airline to follow suit.