MADRID, Sept 12 - Formula One world champion Fernando Alonso has launched a scathing attack on Michael Schumacher following the German driver's announcement that he will retire at the end of the season.

The 25-year-old Spaniard accused seven-times world champion Schumacher of being the most unsporting driver in the history of the sport.

He also compared Schumacher's departure unfavourably with that of French footballer Zinedine Zidane whose last act before retiring was to be sent off for headbutting Italian defender Marco Materazzi in the chest during the World Cup final.

"Zidane retired with more glory than Schumacher," Alonso was quoted as telling Radio Marca in Tuesday's edition of the Spanish sports daily.

"Michael is the most unsporting driver with the largest number of sanctions in the history of Formula One.

"That doesn't take away from the fact that he has been the best driver and it has been an honour and pleasure to battle against him.

"Everyone has their time and you have to respect his decision. Things will be more equal now."

Alonso also attacked what he saw as institutional bias in favour of Schumacher and his Ferrari team.

"In Formula One there are commercial and political interests," he said.

"We are talking about the most successful driver in history and a little bit of help has never gone amiss. Quite often they go over the line of what is acceptable and it is inexplicable."

NOT RACING

Alonso was demoted five places to 10th on Sunday's Italian Grand Prix starting grid after stewards ruled that the Spaniard had impeded Ferrari's Brazilian Felipe Massa.

The Renault driver, who was adamant he had not blocked Massa, failed to finish the race because of an engine failure and his championship lead over Schumacher was slashed from 12 points to two after the German won the race.

"No one is going to believe the penalty I was given for a long time to come," Alonso said.

"The excuse they gave was far from honest... It isn't good for our sport.

"Sometimes you think about not racing, but you get over that quickly enough and put on you helmet. I was 100 percent convinced that no matter where I started I could earn some points and stay ahead.

"One thing I am clear about, though, is that he who laughs last, laughs longest.

"Anyone can win the remaining races and if we get things right in two of the three races that are left the world championship will be ours."

Alonso and Schumacher will renew their rivalry on the track at the Chinese Grand Prix on October 1.