Spa-Francorchamps, Belgium - Ferrari's Felipe Massa was Sunday declared winner of Formula One's Belgian Grand Prix after race stewards slapped a 25-second penalty on Lewis Hamilton.

The ruling moves McLaren-Mercedes driver Hamilton down to third place behind BMW-Sauber's Nick Heidfeld.

After looking at an overtaking manoeuvre in the 42nd of the 44 laps at Spa the stewards decided that Hamilton had gained an unfair advantage over Ferrari's Kimi Raikkonen by cutting a chicane.

Raikkonen later crashed out as Hamilton went on to win, more than 14 seconds ahead of Massa.

The race stewards' decision cuts Hamilton's lead over Massa in the drivers' standings to just two points.

The 23-year-old Briton has 76 points with Brazilian Massa on 74. BMW Sauber driver Robert Kubica (58) is third ahead of Raikkonen (57), whose hopes of winning the 2008 title are now fast dwindling.

Before the penalty, Hamilton had extended his lead over Massa to eight points.

"I don't understand the argument," Mercedes sports chief Norbert Haug said of the ruling. "I never expected this."

The ruling capped a turbulent race in which Hamilton grabbed a dramatic victory on the track after rain led to a chaotic but thrilling climax at the classic Spa-Francorchamps circuit.

The McLaren-Mercedes driver had to fight to keep his car on the track after he had duelled with Raikkonen, who slid off into a wall on the penultimate lap.

Massa finished second, while Heidfeld's gamble to make a late change of wet-weather tyres paid off when he jumped from eighth to take the chequred flag in third position.

Renault's Fernando Alonso, who also made a late tyre change, was fourth ahead of Sebastian Vettel (Toro Rosso), with Robert Kubica (BMW Sauber) sixth, Sebastien Bourdais (Toro Ross) seventh, and Timo Glock (Toyoto) eighth.

However the stewards also ruled against Glock, who was handed a 25-second penalty for overtaking Red Bull's Marc Webber during a yellow-flag phase near the end of the race.

The penalty means the German moves down to ninth place, with the point earned for eighth place now going to Webber.

Raikkonen led for most of the race on Spa's 7.003-kilometre circuit, the longest on the F1 calendar, and after a brilliant start from fourth on the grid appeared to be on his way to a fourth successive Belgian GP win.

But rain which begun to fall with six laps remaining led to a dramatic race climax as Hamilton closed in and the two duelled for the lead over the final laps.

However in what proved to be a contentious manoeuvre, Hamilton was forced to cut a chicane at the end of lap 42 of the 44 laps as Raikkonen defended a challenge from the Briton on the turn.

Emerging back on the track in front, Hamilton allowed Raikkonen to overtake but immediately launched another attack on the straight to go past the Ferrari.

Both drivers then struggled to retain any sort of grip. Hamilton slid off to hand the lead back to Raikkonen, who almost immediately lost it again by spinning on the greasy surface, before his race ended when he lost all control and thudded into a wall.

After the race, none of the McLaren team saw anything wrong in the late battle for the lead, and Hamilton appeared confident it was a fair contest.  "It was an experience and a half," Hamilton said.  "I was praying for rain. I wanted it to come because I knew how to deal with it. The heavens opened and I saw Kimi begin to back off and to brake a bit earlier.

"I was going reasonably wide at turn 12 but (Nico) Rosberg spun and went off where I was coming back on. I went over the grass. It was incredibly tough.

"Kimi pushed me wide. I was a little bit ahead. I was outside on turn one, I had no room and he basically pushed me so I went on the escape route. So I let him past, then got in his tow and he was ducking and diving left and right but I managed to get past him and I was pretty much gone from there."

However Raikkonen, referring to fact that the manoeuvres were under investigation, said: "There are rules about cutting chicanes and getting an advantage but I don't have much to say about it."

Raikkonen won the Belgian GP in 2004, 2005 and 2007 - with Spa absent in 2006 from the F1 calendar - and led the way after capitalizing on an early spin by Hamilton.

Hamilton had got off to a good start from pole but spun on the first corner of lap two, and Raikkonen, who had earlier squeezed past team-mate Massa, took advantage to take the lead.

By the half-way mark Raikkonen enjoyed a six-second lead on Hamilton, but this was reduced to under two seconds after a second pit stop for the drivers.

With dark clouds gathering over the circuit, the question was whether the rain which was forecast would come in time to add some spice to the race. The answer came when the first few drops turned into a shower with three laps remaining.

Hamilton finished the race in 1 hour 22 minutes 44.933 seconds, 14.461 seconds ahead of Massa and 23.844 seconds up on Heidfeld.

The stewards ruling leaves the championship tight going into a home race for Ferrari at the Italian Grand Prix at Monza next Sunday.

With five races left of the season, Ferrari lead the constructors' championships on 129 points, with McLaren on 123 and BMW Sauber on 105.