Bahrain banned all protest gatherings on Tuesday and threatened legal action against groups said to be backing escalating demonstrations and clashes.
The interior ministry order is the most sweeping attempt to quash the anti-government uprising in the Sunni-ruled kingdom since martial law was imposed during the early months of unrest last year.
It sharply increases pressure on political groups from Bahrain’s Shia majority, which has led the protests in support of a greater political voice.
A crackdown on opposition groups could raise complications for Washington and other western allies that have stood by Bahrain’s monarchy during more than 20 months of unrest. The US has important military ties with Bahrain, which hosts the US navy’s 5th Fleet, but it also has called for increased dialogue to ease the tensions.
Shias make up around 70% of Bahrain’s 525,000 citizens, and claim they face systematic discrimination such as being denied top political and security posts. The Sunni monarchy has made a series of concessions – including giving more powers to the elected parliament – but opposition groups say the reforms do little to loosen the ruling family’s grip on power.