Lewis Hamilton will be demoted 10 places on the grid at the French Grand Prix on June 22 as punishment for his pit-lane accident in Montreal.

The Englishman ran into the back of Kimi Raikkonen as the Ferrari driver waited at a red light at the exit. Both were forced to retire.

Race stewards gave Williams driver Nico Rosberg, who ran into the back of Hamilton's car, the same penalty.

"I've no argument with the stewards," said Hamilton after the decision.

The punishment capped a weekend turned sour for Hamilton, who had qualified in pole position and was seemingly on his way to back-to-back wins in Montreal.

The McLaren driver had built up a 6.8-second lead over Kubica before the safety car emerged on lap 17 following Adrian Sutil's crash.

When the pit lane reopened two laps later, Hamilton took on board enough fuel to see him through to the end of the race.

But in his hurry to get back out, and not lose sight of Raikkonen and BMW Sauber's Robert Kubica who had both refuelled first, he ran into the back of Raikkonen.

Raikonnen and Kubica had been lined up side-by-side waiting for the pit lights to turn green, signalling that they could return to the track.

"I saw the two guys in front of me battling in the pit lane and all of a sudden they stopped," explained Hamilton.

"I saw the red light but it was too late to stop. I don't think it's a racing incident. It's just unfortunate when this stuff happens.

"It is a lot different if you crash into the wall and you are angry with yourself.

"I apologise to Kimi if I ruined his race. I would rather neither of us be out. I was so quick I was breezing it.

"We'd looked so strong for the whole weekend though, so at least we can leave Montreal confident that we have a package that will enable us to fight for the world championship from here on in."

Kubica, who went on to claim a maiden Grand Prix win in Montreal, was happy to emerge unscathed from the incident.

"We all pitted together," said the Pole. "I saw Kimi side by side with me.

"Then I just heard a big shunt and saw Kimi's moving and realised it was Lewis. He was over Kimi's rear wing.

"I just kept concentrating waited for the green light and managed to pull away well.

"I have to thank him that he shunts Kimi and not me."

McLaren team principal Ron Dennis defended Hamilton's error but was keen to put a dismal weekend in Monaco behind him as the team aim to recapture the lead in the drivers' championship.

"No racing driver would deliberately put himself out of a Grand Prix, and the plain fact is that Lewis didn't realise that the cars in front of him were coming to a halt until too late," Dennis said.

"It's difficult for a driver to decide whether to focus on the lights or on the cars ahead in situations like that.

"For a team that exists to win, today was a very disappointing day. But the fact is that we had the pace and therefore the capability to win, which is of course encouraging."