The Bahraini government has said it is "confident" the Grand Prix will not be disrupted by continuing clashes between pro-democracy demonstrators and security forces.

Violent disturbances have been intensifying in recent days with around 50,000 anti-government protesters gathering around the capital Manama, just 25 miles away from where the controversial race meeting is under way.

Opponents have fought pitched battles with security officials, with claims surfacing that protester Salah Habib Abbas, 37, was killed by shotgun pellets fired by riot police on a rooftop during an overnight raid.

Despite the ongoing violence, Fahad al Binali, spokesman for the Bahrain Information Affairs Authority, said measures were in place to prevent any disruption to the controversial Formula One event.

He said: "Guaranteeing is difficult, but we have the best measures in place. I'm very confident and assure everybody about safety." Mr al Binali said he was "surprised" some protesters had campaigned against the race, saying it had provided them with "a platform" to a global audience.

Foreign Secretary William Hague spoke to the foreign minister of Bahrain to express the Government's "concern" about the violence. He called on the Bahraini authorities for "restraint in dealing with protests including during the Formula One race" and urged "further progress in implementing political reforms".

Meanwhile Mercedes and McLaren team bosses Ross Brawn and Martin Whitmarsh criticised British politicians for what they believe is a belated stance on the Grand Prix.

Mr Brawn said: "I find it very frustrating that politicians in the UK were saying we should withdraw once we got here. Why didn't they say anything beforehand?" He added: "For somebody to try and make Jenson Button or Lewis Hamilton determine the foreign policy of the country is wrong."

David Cameron has resisted pressure to call for the cancellation of the event, insisting it was a matter for the F1 authorities. The 2011 race was cancelled as international criticism grew over the bloodshed and the Foreign Office has advised British motor racing fans against travelling to this year's event.

On the track German Sebastian Vettel won the race for Red Bull after starting from pole position.