Preparations are continuing for Sunday's controversial Formula One Grand Prix in Bahrain despite clashes between security forces and protesters and a firebomb scare for members of one of the teams involved in the race.

Security forces on Thursday fired tear gas and stun grenades at hundreds of anti-government protesters chanting slogans against the race.

Marchers in the capital Manama also called for the release of a jailed activist, Abdulhadi al-Khawaja, who has been on a hunger strike for more than two months.

Meanwhile two members of the UK-based Force India team were reported to have asked to go home after a firebomb exploded near a car they were travelling in with two colleagues as they were stuck in traffic near the Sakhir circuit on Wednesday night.

The Bahrain race circuit said in a statement that a Molotov cocktail had landed in the vicinity of their vehicle, during "an isolated incident involving a handful of illegal protesters acting violently towards police".

Force India said that nobody had been hurt in the incident. 

Marc Priestly, a F1 journalist in Manama, told Al Jazeera that "fortunately no one was injured in the incident, [but] it could have been very, very serious."

"The mood across the paddock is certainly one that would suggest that people, given the choice, would rather not be here," Priestly said.

Speaking to reporters, Pedro de la Rosa, the chairman of the Formula One Grand Prix Drivers Association, said safety was "not a concern," adding that he had full faith in the decision by motor sport authorities to hold the event despite mounting tensions in the kingdom.

Bahrain opposition groups have criticised the decision to stage Sunday's race, which was cancelled last year because of unrest.

Bahrain's Shia majority began an uprising in February 2011 seeking a greater political voice in the Sunni-ruled kingdom.