PARIS (AFP) - French tennis player Mathieu Montcourt, who was found dead outside his apartment near Paris early Tuesday, died of a heart attack, a police source told AFP on Thursday.

"The autopsy revealed a heart attack (suffered by) Mathieu Montcourt and toxicological analyses showed up negative. It was death from natural causes," the source said.

Montcourt will be cremated on Friday just outside Paris after which relatives will join French tennis officials for a memorial at Roland Garros, home of the French Open.

The body of the 24-year-old, ranked 119th in the ATP rankings, was found by his girlfriend outside their ground floor apartment in the Paris suburb of Boulogne-Billancourt.

She alerted police, who said there were no indications that Montcourt had been attacked.

A tennis professional since 2002, Montcourt reached a career best world ranking of 104 in June after qualifying for the main draw at the French Open and reaching the second round where he lost in four sets to Radek Stepanek.

His last tournament was in the Croatian town of Rijeka late June where he reached the semi-final of a Challenger event.

His career was badly hit in August last year when he was banned for eight weeks and fined 12,000 dollars for betting on the Internet on the outcome of matches.

Montcourt appealed against the ban and the Lausanne-based Court of Arbritation for Sports reduced the sanction by two weeks citing the small sums of money involved - 192 dollars on 36 matches - and the fact that he did not bet on matches in which he was playing.