Lewis Hamilton suffered a setback in his attempts to win his first Formula One world title today when the FIA rejected his appeal against demotion at the Belgian Grand Prix.

The Briton will now head into this weekend's night-race in Singapore with a slender one-point lead at the top of the driver's championship.

Hamilton had hoped to have his demotion from first to third place at Spa overturned which would have seen his lead increase to seven points over Ferrari's Felipe Massa, but the five judges have upheld the stewards' ruling.

The 23-year-old was handed a 25-second penalty after the race for an illegal overtaking manoeuvre on Kimi Raikkonen and even appeared in person in Paris yesterday for four and a half hours to argue his case.

But there was disappointment this afternoon when the FIA, the sport's governing body, ruled his appeal was 'inadmissible'.

In a statement, the FIA said: "At the Grand Prix of Belgium, run on 7 September 2008, and counting towards the 2008 FIA Formula One World Championship, the Stewards of the meeting imposed a drive-through penalty upon the driver of car No22, Lewis Hamilton, for a breach of Article 30.3 (a) of the 2008 FIA Formula One Sporting Regulations and Appendix L, Chapter 4, Article 2 (g) of the International Sporting Code.

"As the drive-through penalty was imposed at the end of the race, 25 seconds were added to the driver's elapsed race time in accordance with Article 16.3 of the FIA 2008 Formula One Sporting Regulations.

"Article 152 of the International Sporting Code states that drivethrough penalties are 'not susceptible to appeal'.

"Having heard the explanations, the Court has concluded that the appeal is inadmissible."

There are now only four races left in the season, which finishes at Interlagos in Brazil, with Felipe Massa second on 77 points and BMW's Robert Kubica a further 13 behind in third place.