Authorities in Bahrain announced the arrest of seven people suspected of carrying out or plotting attacks in the kingdom.
Five of those detained were believed to have formed a cell of the Al-Ashtar Brigades militant group and were accused of being behind three attacks on the armed forces, said Security chief General Tariq al-Hassan.
Explosives and chemicals used to make homemade bombs were seized during the arrest operation, the same source said.
The two other people arrested were accused of carrying out surveillance in preparation for attacks on the security forces.
Bahrain has been shaken by sporadic unrest since a crackdown in 2011 on protests led by Shiites calling for democratic reforms and an end to their alleged marginalisation.
Dozens of Shiites, including many regime opponents, have been sentenced in recent years to prison for violence that accompanied the protests.
The authorities deny any discrimination against Shiites and regularly accuse Iran of interfering in Bahrain's internal affairs, which Tehran denies.
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