The McLaren driver, Toro Rosso's Sebastian Vettel and Red Bull's Mark Webber, plus team officials, met stewards at the Chinese Grand Prix and watched parts of the Japan race, including amateur footage of an accident that sparked the investigation.

Vettel and Webber collided, and later claimed they crashed because Hamilton was speeding up and slowing down while the field was behind the safety car in wet conditions.

"The involvement of Lewis Hamilton in this incident has also been considered in the light of the evidence given by him, his team manager and in particular all other parties present and no penalty is imposed on him," the stewards wrote after finishing the investigation.

Vettel also had a penalty reduced. He was originally penalized 10 places on the starting grid for the Chinese GP but it was reduced to only a reprimand.

"I am honestly happy with the result and looking forward to the weekend and approach tomorrow and just want to try to win the race," Hamilton said. "It was just really tough today. Now I am relaxed. I can really focus and get a good night's sleep and come back tomorrow and enjoy the weekend."

Before the decision, there was speculation Hamilton could be punished over the Japan incident by being moved backwards on the grid in China, jeopardizing his hopes of clinching the drivers' title in Shanghai.

Hamilton leads the championship by 12 points, ahead of McLaren teammate Fernando Alonso with two races remaining. He will win the title on Sunday if he finishes ahead of Alonso or only drops one point relative to the Spanish driver.

Vettel and Webber left the stewards' meeting after about 30 minutes but Hamilton and the McLaren team manager Dave Ryan discussed the incident for a further 20 minutes with stewards, Tony Scott Andrews, Hermann Tomcyk and Gao Xuechun.

"Having heard the evidence of all concerned and viewed both then original film of the incident which was available to the stewards at Fuji as well as the new film (which in reality adds little, if anything, to the original film) what has become apparent is the view clearly expressed by all drivers and team managers alike that the conditions at Fuji were exceptionally bad," the stewards wrote.

That influenced their decision to reduce Vettel's sanction.

"Because of these views, the stewards accept that it would be inappropriate to impose the penalty normally applied for an offense such as this. In the circumstances the stewards will reduce the penalty imposed upon Vettel to one of a reprimand."

Webber and Vettel were both critical of Hamilton at a news conference Thursday.

Webber said Hamilton was slowing and speeding up behind the safety car, hampering the drivers behind him, especially with the water spray affecting visibility.

"It definitely contributed to Sebastian hitting me up the back," Webber said.

Many cars were trying to keep the heat in their tires by accelerating and slowing or swerving from side to side.