Christophe Fauviau was devoted to his children's tennis careers

Christophe Fauviau, 46, appeared in court in Mont-de-Marsan on charges of unintentionally causing a death by administering noxious substances.

He is accused of spiking water bottles of 27 of his children's opponents with a drug causing drowsiness.

If found guilty, the retired soldier faces up to 20 years in prison.

Prosecutors will tell the court that Mr Fauviau is suspected of drugging 21 rivals of his daughter, Valentine, 15, and six of his son, Maxime, 18, between 2000 and 2003.

He allegedly used the drug Temesta - an anti-anxiety medicine which can cause drowsiness - to improve his children's chances in the matches.

All the opponents concerned, nine of them aged under 15, complained of weak knees, dizziness, nausea or fainting during the games. Some were later taken to hospital.

'Diminished responsibility'

Police investigations began after a player beaten by Maxime Fauviau died in a car crash while driving home after the amateur tournament in July 2003.

Twenty-five-year-old teacher Alexandre Lagardere had suddenly suffered great fatigue and loss of balance while playing the teenager.

The parents of Alexandre Lagardere attended the trial opening

On his arrest in August 2003, police said Mr Fauviau had admitted spiking the drinks of Mr Lagardere and two others.

Ahead of the trial, his defence lawyer, Pierre Blazy, said the prosecution would have to prove a direct link between the administration of the drug and Mr Lagardere's fatal crash.

Mr Blazy told France's Sud-Ouest newspaper that his client had been in a state of diminished responsibility at the time of the incident and had sought psychotherapy while in custody.

Suspicion quickly fell on Mr Fauviau, from the south-western town of Dax, because of complaints by two other players who had competed against Maxime in preceding weeks.

One allegedly saw Mr Fauviau tampering with a water bottle before the game and gave it to police. It tested positive for Temesta.

The ex-helicopter pilot was said to be devoted to the tennis careers of his children, particularly that of Valentine, who was already high in the rankings.

A verdict is expected in the case on 10 March.