Bahraini security forces have fired stun grenades at protesters outside a cultural exhibition in Manama ahead of Sunday's Formula 1 Grand Prix.

Demonstrators are demanding the release of Abdulhadi al-Khawaja, an activist who has been on hunger strike in prison for more than two months.

Formula 1's governing body only decided to go ahead with this weekend's race at the last minute, and the Bahraini authorities say it will take place without any problems.

Tim Allman reports.