(CNN) -- The Bahrain Grand Prix will act as a unifying force amid the nation's unrest, the Bahraini government said Friday, while opposition activists accused the Gulf kingdom's rulers of cracking down on demonstrations.
The Bahrain Grand Prix is set to run Sunday.
"The government guarantees the safety of everyone. We are very confident about our security measures that we have in place," Fahad Albinali, spokesman for the Bahrain Information Affairs Authority, told CNN's Becky Anderson.
Crown Prince Salman bin Hamad Al-Khalifa told reporters that canceling the race would play into extremists' hands, according to a report Friday in the state-run Bahrain News Agency.
"The Formula 1 race allows us to build bridges between communities, get people working together," said the crown prince. "It allows us to celebrate our nation as an idea that is positive, not one that is divisive."
He and Albinali echoed a government statement issued earlier that reported there are no problems.
"The three-day Bahrain Grand Prix began today absolutely safely and without incident. Bahrain is a safe country and there is no reason for any Formula 1 team to have concerns about security," the government said, noting that preliminary events kicked off Friday.
The statement was in response to remarks by former lawmaker Mattar Mattar, who said the government had increased the number of arrests in the days leading up to the event.
"So the government decided to control the situation just by excess of force and by using more violence, and this is the policy that the regime has used always," he said.
A human rights activist, Nabeel Rajab, also accused the government of detaining and torturing "at least half" of the Formula 1 staff in Bahrain.
"We don't want Formula 1 to look like it is a sport of dictators. We need it to look like it is a sport of those people who love the sport," he said.
The crown prince said demonstrations that took place Friday were part of the political process, like in any country, the Bahrain News Agency reported.
Claiming that some security personnel who had been heavy-handed in the past have been held accountable, he condemned violence on all sides -- including by demonstrators trying to get, in his words, the world's attention.
Specifically, the government denied that any torture or mistreatment of Bahraini racing employees has occurred, adding that it takes such allegations seriously.
"The Grand Prix has always had widespread domestic support and will clearly act as an important unifier, following a challenging period where significant and important lessons have been learnt," the government statement said.
The controversy about the race spilled over into cyberspace, with the apparent hacking of the Formula 1 website. On Friday, the site was shut down, and a message was left condemning the government and the Formula 1's decision to hold the race. Later Friday, the website was completely inaccessible.
The loose collective of hackers known as Anonymous, in a purported news release, warned the Bahraini government and Formula 1 that their websites would be targets of the group.
As of Friday, "the entire global Anonymous will begin to take up the cause of the Bahrain revolution," the statement said.
To the Formula 1 organizers, it said, "Anonymous will turn your web site ... into a smoking crater in cyberspace. We will also jam your phone lines, bomb your e-mail inboxes -- and wreck anything else of yours we can find on the Internet."
On Friday, tens of thousands attended an anti-government demonstration in the capital, Manama, and many then began marching toward the former Pearl Roundabout, the center of last year's revolt, activist Mohammed Muscati told CNN.
Some of the protesters called for the release of Abdulhadi al-Khawaja, a human rights activist who has drawn international attention with a hunger strike he's sustained for more than two months. Four U.S. senators -- Richard Durbin, Robert Casey, Marco Rubio and Ron Wyden -- sent a letter to the crown prince urging him to release al-Khawaja, according to rights advocacy group Freedom Now.
According to one of his daughters, Maryam, he has now stopped drinking water and taking fluids intravenously. Al-Khawaja asked to see his lawyer to write his will, but both his lawyer and the Danish ambassador have been denied access to him, she said, stressing her father may only have hours left to live. He holds Danish citizenship.
Furthermore, she said Zainab al-Khawaja, an activist and al-Khawaja's daughter, was arrested when she went to the hospital to try to visit her father. She was subsequently released, Maryam said.
Government spokesman Albinali denied that al-Khawaja was in serious condition. He had no immediate comment on the daughter's reported arrest.
"He is stable ... There is no immediate risk to his life. We're monitoring the situation now," Albinali said.
Al-Khawaja was arrested in April 2011 for his role in anti-government protests that began a month earlier with demands for political reform and greater freedoms in the Sunni-ruled, Shiite-majority nation.
In June, Bahrain found him and seven other Shiite opposition activists guilty of plotting to overthrow the country's Sunni royal family.
He can appeal his life sentence during a hearing April 23, the government has said.
Friday's protesters were confronted by riot police, and in the ensuing clashes police used tear gas and stun grenades to disperse the crowd, according to Muscati, the activist.
Muscati's group, the Bahrain Youth Center for Human Rights, reported that 15 protesters were injured overnight in clashes with riot police.
Activists also protested in villages close to the Formula 1 event, where they tried to disrupt the main road from Manama to the race.
There are mounting fears that civil unrest in Bahrain could upend the race and pose a threat to Formula 1 teams and fans. Last year's race was canceled twice because of the unrest, but the sport's governing body said Friday the event would go ahead as planned despite tension on Bahrain's streets.
Meanwhile, Bahrain has declined to extend the visas of non-sports reporting crews from CNN, Reuters and other news agencies and told them they would not be allowed to stay for the race, which is a big draw, both in terms of investment and fans.
Formula 1 is the world's most popular motor sport, and races have a TV audience of more than 500 million. When Bahrain canceled the race last year, it lost an estimated $480 million to $800 million of investment that would have come from hosting it.
The unrest in Bahrain makes hosting the race precarious because the racers must pass through some areas where clashes have occurred to get to the circuit, which is in the desert.
CNN's Fred Pleitgen, Mohammed Jamjoom, Gary Morley and Peter Wilkinson contributed to this report.