SILVERSTONE, England, July 8 (Reuters) - World championship leader Lewis Hamilton vowed to improve his performance after mistakes cost him any chance of victory in Sunday's British Grand Prix.

Hamilton finished third behind McLaren team mate Fernando Alonso and Ferrari race winner Kimi Raikkonen in what is still a sensational start to his debut season in Formula One.

Asked what he needed to do to go on and win the world title, the 22-year-old told a news conference: "I think I need to step up my game, which I intend to do.

"As a team we need to push, as always, but to try to push a bit more if we can.

"As a driver, I'm still learning...we're going to a few tracks that I know, so it should really make the weekend a little bit easier -- but it doesn't.

"I've been here before, but I've struggled in terms of pace."

Hamilton's problems began with a messy first pitstop that left the early race leader in third place, after he tried to jump the gun before his engineers had extracted the fuel hose.

"I made a mistake in the pitstop," he said.

"I thought the lollipop was lifted and I went. I don't know how many seconds I lost."

A bigger problem was getting enough sheer speed out of his car, despite his barnstorming final qualifying lap to take pole position on Saturday.

WRONG DECISION

"I made a wrong decision with the set-up," he lamented. "I chose a different rear end to Fernando and I think it really caused me problems in the race.

"Even in qualifying we didn't really have the pace we should have had, and it was too late by then to change.

"It's a good lesson...we have to look forward and hope to be better in the next race."

Despite any disappointment in his home grand prix, Hamilton was still able to leave Silverstone with an unprecedented ninth top-three finish from as many races.

"We could have had a better result ...but you have to look on the bright side," he said.

"It's nine podiums in a row. I don't know if that's ever been done, but I'm very happy with that."

Hamilton also spared a thought for the Silverstone crowds, who had been hoping to celebrate a third victory in his fledgling F1 career.

"The fans have been tremendous this weekend," he said. "Without their support it would have been a much harder race. I knew they were with me all the way."