London issues warning for Bahrain LONDON, Feb. 14 (UPI) -- London warned of a general threat from terrorism in Bahrain as demonstrators mark a so-called day of rage by protesting against the Sunni monarchy. The British Foreign and Commonwealth Office warned that "some groups" have called for mass demonstrations Tuesday to mark the first anniversary of a Shiite uprising. "There is a general threat from terrorism in Bahrain," the warning read. Terrorists continue to issue statements threatening to carry out attacks in the (Persian) Gulf region. Bahraini forces responded with stun grenades in an effort disperse protesters, al-Jazeera reports. Witnesses told the Arabic news channel demonstrators were chanting "down with (King) Hamad." The official Bahrain News Agency reported little about the unrest other than to say "saboteurs" were arrested for disrupting traffic. Bahrain was swept up in the so-called Arab Spring that erupted after a December 2010 protest suicide in Tunisia. As many as 50 people were killed and an independent commission of inquiry concluded state security forces used unnecessary force when responding to the Shiite uprising. Bahrain's King Hamad bin Isa al-Khalifa told German news magazine Der Spiegel this week his country was headed in the right direction, however. The warning from London advised British citizens to "maintain a high level of security awareness, exercise caution, particularly in public places and on the roads and avoid large crowds and demonstrations."