The Associated Press reports: Riot police in Bahrain fired tear gas and stun grenades Friday as tens of thousands of protesters staged the biggest anti-government demonstrations in weeks in the divided Gulf nation.

Opposition groups called for major rallies after a prominent rights activist, Nabeel Rajab, was placed back in detention earlier this week on fresh charges linked to his social media posts.

Bahrain has experienced near daily protests for 16 months caused by an uprising by the kingdom’s Shiite majority seeking greater political rights from the Western-backed Sunni monarchy. At least 50 people have died in the unrest since February 2011.