Bahrain arrested on Thursday five opposition activists calling for democratic reforms, raising the number detained in the past week to 19, opposition sources said.
The wife of one of the detainees said her husband, Jaafar Salman Salil, was taken by police along with political leaflets they found after searching their home.
Defying a government ban, opposition groups have circulated a petition demanding constitutional amendments to grant more powers to parliament's elected assembly, which has the same status as a chamber appointed by King Hamad bin Isa al-Khalifa.
The suspects have been charged with attempts to change the political system and undermine security in the pro-Western Gulf Arab state, which is the Gulf's banking hub and home to the US Navy's Fifth Fleet.