BBC News' Neil Bennett: This result will surprise few people

"The court of appeal has decided to overturn the decision of the stewards and therefore the original result of the race stands in its entirety," International Automobile Federation (FIA) President Max Mosley told a news conference in Paris.

The ruling means the Formula One world championship will be decided in the final race of the season in Japan on 31 October.

Ferrari's Eddie Irvine goes into the race with a four-point lead after the court ruled he should regain the first place and 10 points he lost when he was disqualified from last Sunday's race in Sepang.

His team-mate Michael Schumacher was restored to second.

Eddie Irvine finished first after all

If the decision had gone against Ferrari, the championship would have been won by McLaren's Mika Hakkinen.

Hakkinen gained what would have been an unassailable lead when the two Ferrari drivers were disqualified after a post-race car inspection uncovered a discrepancy over the size of aerodynamic aids on their cars.

However the FIA's five-member International Court of Appeal ruled that the dimension in question fell within an allowable 5mm tolerance.

High price for McLaren

Hakkinen seemed to accept the decision, saying: "The events of the last week are now behind us and I am - as always - focusing on the next race."

"I will do my best to win the race and the world championship."

Ron Dennis: "It's a bad day for the sport"

However McLaren's Managing Director, Ron Dennis, said it was "a bad day for the sport".

He said: "A way has been found ... to provide a reason for the appeal to be upheld.

"Everybody wants to have an exciting race in Japan, but I think that the price we have paid is too great."

Ferrari delight

Irvine said his team had been "totally exonerated".

FIA President, Max Mosley: "The original result stands in its entirety"

"It was a pure technical matter that the car was legal all along, which is fantastic.

"I didn't want people to think that it was political, it was business, or any of that sort of carry on that got us reinstated," he said.

Ferrari's chairman Luca di Montezemolo said the ruling "acknowledged that our cars were perfectly normal".

He said the decision also "silenced many unfair interpretations which displeased us so much".

Dozens of Ferrari fans braved the rain to celebrate in front of the company's headquarters in the northern Italian town of Maranello.

Commercial consideration denied

Some correspondents questioned whether the court had ruled in favour of Ferrari simply to boost public interest in the final race of the season.

FIA President Max Mosley: "Judges had no choice"

But Mr Mosley denied this, saying: "Five independent judges had the benefit of listening in great detail to the evidence."

He said that at the hearing the FIA's technical delegate had measured the "turning vane" and admitted it fell within the tolerance in every respect.

"No judge would have any alternative but to make the finding they found," he added.

Earlier, FIA vice-president Bernie Ecclestone said the disqualification had been "nonsense".

At the news conference, Mr Mosley said Mr Ecclestone had no power over rule enforcement and that the judges would not have paid any attention to his views despite his financial power in the sport.

FIA criticised

The BBC's Motor Racing Correspondent Jonathan Legard: "Any review however is for the future"

Mr Mosley said that at the hearing Ferrari had with "some justification" criticised the FIA's methods of measurement. The judges also questioned the clarity of the regulation itself.

Mr Dennis said he was convinced that Ferrari had made an honest mistake over the size of the aerodynamic aids.

But he added: "I think it is slightly hypocritical to say there is no performance influence because that is a very aerodynamically critical area on the car."