Lewis Hamilton was beaten by Sebastian Vettel at Spa on Sunday. Picture: Geert Vanden Wijngaert / AP Photo.

Spa-Francorchamps, Belgium - Lewis Hamilton said Ferrari had 'trick things going on' with their car after Sebastian Vettel won Sunday's Belgian Grand Prix but emphasised he was not accusing his Formula One rivals of doing anything illegal.

The championship leader's comments aroused immediate interest with the Mercedes driver, who finished second at Spa and saw his overall lead cut to 17 points, facing questions afterwards.

"We all have trick things going on our cars," said the Briton, who had started on pole position but was swiftly overtaken by Vettel - who then raced untroubled and finished 11 seconds clear.

"Trick is just a word for something special, I guess," added Hamilton.

Asked whether he felt Ferrari were doing something illegal, Hamilton initially said he had no idea what was on the Italian team's car so could not say either way.

He said Ferrari had showed some serious pace in the race, particularly on the straights even if Mercedes were quicker in other areas.

"I'm not saying that there is anything illegal," Hamilton added more forcefully as reporters returned to the subject.

"Trick is just something that helps you bring that extra bit of performance, that's all I mean. So please don't read into it and please don't twist my words and say that I say they are doing anything illegal, because they're not.

"They just out-performed us today and we've got to work harder. There's things they might have on the car that we might not and vice-versa. We've got to try and find out what and improve on that."

Vettel and Hamilton now have five wins each and the Italian Grand Prix at Monza, Ferrari's home race and last of the regular European season, is next up.

Mercedes team boss Toto Wolff said Ferrari were very innovative and he had faith in the governing body to police things.

Formula One race director Charlie Whiting told reporters he was "quite amused".

"We know quite a lot about the Ferrari car and there is no way Lewis would know anything about the Ferrari car," he added. "They're doing a good job at the moment and Mercedes have got to try and counter that, haven't they?

"If he says they've got a few tricks going on that car, well clearly they have got things going on which are giving it performance which all of us in the FIA are aware of and obviously are happy with."

Reuters