Bahraini protesters and riot police clash on the streets of Nuwaidrat, south east of Bahrain's capital Manama.<br/> <br />These amateur videos uploaded to a social media website purport to show demonstrators shouting "Down with King Hamad."<br/> <br />Reuters cannot independently verify the content of the videos.<br/> <br />The unrest comes in the run up to Sunday's Formula One Grand Prix - the biggest sporting event hosted by Bahrain.<br/> <br />Several people have been arrested on the island kingdom amid heightened security ahead of the race.<br/> <br />The U.S. allied Gulf Arab state has been hit by unrest since pro democracy protests broke out in early 2011.<br/> <br />The Grand Prix was cancelled that year due to protests in which at least 35 people were killed.<br/> <br />Last year the race went ahead against a backdrop of violent clashes between police and protesters.
