Mercedes' British driver Lewis Hamilton celebrates his Italian Grand Prix victory in Monza on Sunday. Photo: CFP

Lewis Hamilton extended his lead in this year's drivers' world championship to 53 points on Sunday when he drove to a flawless and consummate victory in the Italian Grand Prix.

His nearest title rival, Mercedes ­teammate Nico Rosberg retired with a blown engine with two laps to go when placed third.

There was confusion in the immediate aftermath when Mercedes were summoned to the stewards to explain the possibility that Hamilton's car had been running on lower-than-allowed tire ­pressures.

"We got word towards the end of the race that some cars' tire pressures were being checked, and have been ­summoned to the stewards," Mercedes chief Toto Wolff explained.

Hamilton led from pole position to the checkered flag, leading all the way and surviving a nervous period ­during the final laps when he was aware of ­possible problems.

His points margin makes him a clear favorite to defend his crown and claim his third world title during the seven ­remaining races of the season.

The newly blond defending two-time world champion came home 25 seconds ahead of Sebastian Vettel of Ferrari with former local hero Felipe Massa finishing third for Williams, repeating his podium of last year.

For Ferrari, it was a day to celebrate as Vettel revelled in his first race for the team on their home track.

Hamilton's win was his second in succession at the Autodromo Nazionale, his third in all at the famous old circuit, his seventh of the season and 40th of his career.

"Those last few laps were not cool man," Hamilton told his engineer over the team radio in reference to being told to push hard - perhaps to offset any ­potential penalty imposed over illegal tire pressure.

Behind Massa, Finn Valtteri ­Bottas came home fourth in the second ­Williams ahead of Kimi Raikkonen - who stalled on the first row - in the ­second Ferrari and Mexican Sergio ­Perez of Force India.

Nico Hulkenberg came home seventh in the second Force India ahead of ­Australian Daniel Ricciardo of Red Bull, Marcus Ericsson of Sauber and Russian Daniil Kvyat in the second Red Bull.