Mystery over tycoon's air death

Paul Louis Halley was the seventh richest man in France

An air crash that killed one of the world's richest men is likely to remain a mystery after an official report could not say how it happened.

Investigators say they have reached "no definite conclusion" as to why the light aircraft went down, carrying French billionaire Paul Louis Halley.

Mr Halley, 69, his wife and the Belgian pilot died near Oxford's airport.

The Air Accidents Investigation Branch found no technical fault but did not rule out pilot error in the 2003 crash.

Investigators said it was possible the pilot, Hans Frans Walter Brams, 46, "might have been distracted by a bird" as he tried to land the Socata TBM 700 aircraft on 6 December.

Mr Halley co-founded the retailer Promodes which merged with the French supermarket giant Carrefour in 1999.

The four-seater plane narrowly missed a busy dual-carriageway

With a fortune estimated at £2.2bn, he was the seventh richest man in France and 104th on a list of the wealthiest people in the world published in 2003.

After the crash, French Prime Minister Jean-Pierre Raffarin described Mr Halley as one of the most brilliant and appealing characters the French business world had known and a "shining personality".

Mr Halley's wife Annik Jacqueline, 63, was also killed as the plane went into an uncontrolled roll and struck the ground to the west of the airport, narrowly missing a dual carriageway.

Mr Brams had been given clearance to land, after flying the couple in from Brussels.

The AAIB said the pilot could have been distracted by something in the aircraft, become briefly incapacitated, or might have been attempting a "go-around" - in which a pilot decides at the last minute not to land but circles the airfield again before making another attempt.

However, the report concluded it was "impossible to successfully determine a specific cause or causes of this accident".