Bahrain's main Shia Muslim groups have suspended participation in reconciliation talks with the Sunni-led government after the detention of an important opposition figure.
Bahrain's public prosecution said Khalil al-Marzooq, a former deputy parliament speaker, was detained on Tuesday accused of instigating violence and having links to bombings and other attacks.
Marzooq, a senior member of Al Wefaq, the main Shia political bloc, was ordered to be held for 30 days during the investigation.
His supporters claim he was targeted in attempts to punish the opposition after recent criticism from European officials about government crackdowns on dissent.
The decision by the Shia groups closes one of the main channels for dialogue.
Repeated rounds of political talks have failed to significantly close the rifts between the Sunni establishment and Shia factions, who began an Arab Spring-inspired uprising in early 2011 to seek greater political rights.
According to the government, more than 65 people have died in the unrest, but rights groups and others put the death toll higher.