Bahrain's Formula One Grand Prix has been thrown into uncertainty in the wake of escalating political unrest.
As practice sessions began, Bahraini security forces clashed with democracy activists in Shiite villages, AFP reports, and at least 18 people were injured overnight.
The news agency describes how protestors carried photos of the jailed hunger striker Abdulhadi al-Khawaja, and called for King Hamad bin Isa bin Salman Al Khalifa to stand down.
More from GlobalPost: Formula One brings new focus to Bahrain protests
Time says that similar clashes have taken place for months, with the Shiites who account for 70 percent of the kingdom's population claiming they face widespread discrimination.
It adds that additional security troops were deployed around the Bahrain International Circuit and across the capital Manama this week and have used tear gas and stun grenades to disperse opposition rallies.
Meanwhile, Reuters is reporting that two members of the British-based Force India team had requested to go home after being caught up in a petrol bomb incident outside Manama.
They were among four people returning from the Sakhir circuit when a petrol bomb landed on the highway in front of their van and burst into flames.
Following the attack, the Bahrain International Circuit released a statement saying the attack was “an isolated incident involving a handful of illegal protesters acting violently towards police,” the New York Times says, insisting the event would go ahead.
It adds that the government is trying to use the Grand Prix to show that life is back to normal in the Kingdom, where between 40 to 70 people are thought to have been killed since the Arab Spring uprisings began in February 2011.
The Bahrain GP was canceled last year because of anti-government protests, Associated Press explains. Crown Prince Salman bin Hamad Al Khalifa owns the rights to the race.
The news agency says it is among a number of news organizations that have come under pressure from Bahraini officials for covering the uprising, adding that two of its journalists accredited to cover the race had been struggling to get entry visas.
More from GlobalPost: Bahrain facing 'rights crisis' despite reform pledge, Amnesty International says
The BBC says that security had been tightened ahead of practice sessions for Sunday's Formula 1 Grand Prix, after anti-government protesters calling themselves the February 14 Youth Movement promised "three days of rage" to coincide with the event.
The Daily Mail reports that a demonstration was scheduled to take place on the doorstep of the Bahrain International Circuit on Friday afternoon.