A small explosion was heard in the centre of the Bahraini capital Manama on Sunday, three witnesses said, though the cause was not immediately clear.
Police blocked off the road where the incident took place near a government security building in the Adliya district, and a security source at the scene said a car had been damaged by fire. The source did not elaborate and there were no reports of casualties.
The incident took place as the small island kingdom hosted a Formula One Grand Prix, staged about 20 miles south of Manama at the Sakhir desert circuit.
Small bomb explosions occur sporadically in the US-allied monarchy, which has witnessed low-level political unrest since 2011 when the Shi'ite Muslim-led opposition organised demonstrations demanding democratic reforms in the Sunni-led government.
The Duke of York is set to visit he protest-hit country of Bahrain on an official visit.
Prince Andrew's trip begins tomorrow and comes after the Government requested he to travelled to the Middle Eastern state.
Bahrain's government, dominated by members of its royal family, has been accused by campaigning groups of a string of human rights abuses since 2011.
Critics claim little has changed since then and trouble has flared up consistently since those first demonstrations.
Red Bull's Sebastian Vettel took his second win in four races this year as he won this year's controversial Formula One Grand Prix in Bahrain.
Activists clashed with police and blocked roads into the capital in a bid to disrupt the race.
Bahrain's Crown Prince Salman says a reform process is under way, and denies using Formula 1 for political gain.
Bahraini protesters clashed with police today ahead of tomorrow's F1 race in cities across the country, according to activists.
This video, posted by protesters in the northern city of Jidhafs, shows tear gas being thrown amid street battles between activists and police.
ITV News were asked to leave the country and cannot independently verify the video.
Protesters on the streets of Bahrain have been fired on with tear gas by security forces near Aldaih, west of the capital Al Manama, according to protesters.
ITV News were asked to leave Bahrain by the country's authorities yesterday and cannot independently verify these pictures.
Bahrain police fired tear gas in clashes with rioting youths two days before the Formula One Grand Prix in the Gulf kingdom.Read the full story ›
An ITV News crew has been asked to leave Bahrain by the country's authorities as they reported on the violent clashes taking place in the build-up to the Grand Prix.
The team of five, including ITV News special correspondent Rageh Omaar, were filming in the Gulf nation ahead of Sunday's Formula One race where they were yesterday held and questioned at a police station before being released.
The group, who had the necessary visas permitting them to work there, were then again questioned and taken to a police station today, before being told they must leave the country.
An ITV News spokeswoman said: "Our news team were on assignment with visas approved by the Bahraini authorities.
"Having filed a report last night, they were stopped while filming this morning and taken to a local police station for discussions with officers.
"They have since been asked to leave the country, which they are in the process of doing."
The organisers of this Sunday's F1 Grand Prix in Bahrain have vowed that violent protests against the race will not stop it taking place.Read the full story ›
Organisers of the Bahrain Formula One Grand Prix said sporadic protests against the race and unrest in the country do not pose a "direct threat" to the event.
Zayed Alzayani, the chairman of the Bahrain International Circuit, said the security measures put in place at the circuit this week were no different to those for past races.
"We don't feel there is a direct threat to the track nor have we received any threats to the track," Mr Alzayani said. "But we take everything into account. For us, we want to produce an event that is memorable for those who attended".
He insisted that Sunday's race is a unifying force and that a majority of Bahrainis were backing it.
Ticket sales are up 20 percent over past year with 25,000 fans expected at the race, Mr Alzayani said.
"The race has been endorsed by all members of society, including the opposition. If there are people who are against the race, that is fine. They are entitled to express their opinion within the confines of the law", he added.
Amateur videos posted on a social media website allegedly show protesters and riot police clashing in Bahrain ahead of Sunday's Formula One Grand Prix.
One of the clips, said to be shot in the village of Nuwaidrat, purports to show masked protesters throwing petrol bombs and lighting tyres in a street. A second clip, also said to be filmed in Nuwaidrat, purports to show riot police firing in the street.
ITV News and Reuters cannot verify the content of these video clips: