Authorities in the island state, which serves as a US naval base, made the arrests during weeks of unrest in the run-up to a parliamentary election next month.
Officials said activists were members of “a terrorist network with international support” and were planning a campaign of “violence, intimidation and subversion”.
“This sophisticated terrorist network with operations inside and outside Bahrain has undertaken and planned a systematic and layered campaign of violence and subversion,” said Abdulrahman al Sayed, a government prosecutor.
“The leaders of the network have been accused of several crimes including the planning and instigation of violence, conducting a wide ranging propaganda campaign against the Kingdom and seeking to overthrow the regime by force.”
Although the foreign state behind the purported plot was not named, it was widely understood that Iran was the focus of official suspicion. The Bahraini government, which is dominated by the country’s Sunni minority, has frequently accused its Shia Muslim dissidents of collaborating with co-religionists in Tehran.