Police, protesters face off as Bahrain Grand Prix begins MANAMA (Reuters) - Bahrain's Crown Prince rejected calls from human rights activists to cancel this weekend's Grand Prix as pro-democracy opposition groups threatened further protests after days of clashes with security forces. As Formula One cars took to the Sakhir circuit for practice, Crown Prince Salman said that calling off the race on Sunday would play into the hands of "extremists." Speaking to the media alongside Formula One chief Bernie Ecclestone and in front of TV crews broadcasting live around the world, Salman said: "I think cancelling the race just empowers extremists." The government aims to use the Grand Prix as a way of showing that life is back to normal after democracy groups launched an Arab Spring-inspired uprising last year. The protests were initially crushed, but were not stamped out, and demonstrations and clashes are frequent. Human rights organizations and anti-government groups have argued that the race should not be held while what they describe as political repression and rights abuses are taking place in Bahrain. For those of us trying to navigate a way out of this political problem, having the race allows us to build bridges across communities, to get people working together. It allows us to celebrate our nation. It is an idea that is positive, not one that is divisive," the crown prince said. The prince was speaking after two of the 12 teams said their staff had been caught up in incident where protesters threw petrol bombs on their way back from the track to hotels in Manama. The Force India team missed Friday's second practice for safety reasons to make sure staff could get back to their hotels safely before nightfall. On the eve of Friday's practice session, protests had flared in villages surrounding the capital, Manama, away from the race circuit. The Force India team cancelled its second practice on Friday, choosing to stay in its hotel because of security fears. On Friday the British-based team saw burning petrol bombs on the road back to their hotel after an apparent clash between police and protesters. Two team members asked to go home. "A number of rioters and vandals had been arrested for taking part in illegal rallies and gatherings, blocking roads and endangering people's lives by attacking them with petrol bombs, iron rods and stones," a government statement said, citing police chief Tariq Al Hassan. The Sauber team also said it encountered youths with petrol bombs in Thursday's drive home. Bernie Ecclestone, the colorful commercial supremo of the Formula One franchise who arrived at the track on Friday, described general security fears as "nonsense" and said Force India had been offered a security detail. Only small crowds were seen in the grandstand on Friday for an event that has cost Bahrain an estimated $40 million to stage. The opposition is taking the chance to press their case while the world is watching. Opposition parties led by Shi'ite group Wefaq planned to stage a march in a mainly Shi'ite residential district outside Manama later on Friday to demand democratic reforms in a country where the ruling family dominates government. Other protesters could attempt to reach the main highway between Manama and the race track. The leading Shi'ite cleric Sheikh Isa Qassim attacked the government in a sermon on Friday for ignoring popular demands. "This is the crisis of a government that does not want to acknowledge the right of people to rule by themselves and choose their representatives," he said. Manama is under tight security, with dozens of armored vehicles stationed around the capital and the road to the Bahrain International Circuit in Sakhir. Activists say barbed wire has installed near some parts of the main highway. Though life in Manama's main commercial, residential and tourist districts appears detached from the nightly battles, tear gas often floats in from conflict zones around the capital. Activists say riot police are trying to lock Shi'ites down in their villages to stop them gathering on main highways. They say around 95 protest organizers have been arrested in night raids in the past week and 54 people wounded in clashes, with heavy use of birdshot. "They are trying to frighten people after they realized that tear gas did not make the protests to stop," said senior Wefaq member Matar Matar. I think if they fail to stop the protests by this method too, they may reach to the level of carelessness towards killing. While sports journalists poured in to cover the race, non-sports reporters from Reuters and some other news organizations have not been granted visas to visit the Gulf island. "Bahrain wants the international attention brought by hosting a Grand Prix but doesn't want foreign journalists to wander from the race track where they might see political protests," said Robert Mahoney, deputy director of the Committee to Protect Journalists in New York. Ecclestone said he was not aware of the visa rejections faced by some journalists but said he would investigate. "The F1 media spotlight will only highlight the ongoing troubles Bahrain faces in the absence of any serious attempts at political compromise," wrote Chatham House analyst Jane Kinninmont in online magazine Foreign Policy. Writing by Andrew Hammond; Editing by Will Waterman and Giles Elgood