Opposition groups, led by al-Wefaq, have repeatedly called for all protest to be peaceful.

BBC: Dozens injured as violence flares in Bahrain

The main opposition society in Bahrain , Al Wefaq, has called for a major protest on Friday, reports the BBC's Bill Law.

BBC: Fresh Bahrain clashes ahead of Formula 1 race

Earlier this year the leader of Bahrain's main opposition group, al-Wefaq, called for the crown prince to attend talks aimed at ending the unrest.

BBC: Bahrain Crown Prince Salman addresses civil rights

Bahrain's leading opposition party, Al-Wefaq, said Habib suffered a neck fracture, wounds from birdshot, bruises to his hand and leg, and severe burns to his chest and stomach.

CNN: Fresh clashes in Bahrain as protester is buried

Bahrain's state news agency BNA reported the government will take legal action against protesters "who committed violations" during Friday's rally, organized in part by Al Wefaq, Bahrain's main Shiite opposition party.

CNN: Protesters decry unity plans in Bahrain

Khalil al-Marzook, a senior Wefaq leader, was cautiously optimistic about the prince's comments on Friday but warned that "establishing the rule of law without civil and political rights is putting the horse before the cart".

BBC: Bahrain Crown Prince Salman addresses civil rights

In a meeting with the BBC, Sheikh Ali Salman, the leader of the al-Wefaq party, said western countries, including Britain and the US, needed to do more to prevent Bahrain falling prey to extremism by both sides.

BBC: Bahrain opposition seeks UK support as tension simmers