MANAMA  - Authorities in Bahrain said on Saturday they would take legal action against the opposition Al Wefaq group after it held a banned anti-government march, a move the group said was the most serious action against it since mass protests last year. The Interior Ministry said it was acting after the group went ahead with a march on Friday in Manama, the capital, during which six protesters were arrested. “The Interior Ministry holds Al Wefaq responsible for violating the law and encouraging their supporters to participate in a non-sanctioned event,” said a statement from the ministry distributed by the government’s public relations office.

 The opposition has defied government bans on demonstrations before, but this is the first time the authorities have threatened legal action since a protest movement dominated by majority Shi’ite Muslims erupted last February. The United States has called on Bahrain, which hosts the US Fifth Fleet, to engage with the opposition and hold more talks with its representatives. It was not immediately clear what the action might entail, but the move appeared to represent an escalation of government attempts to put pressure on Al Wefaq, a group it has threatened to ban in the past. Opposition parties led by Al Wefaq are demanding full powers for the elected parliament so that it can legislate and form governments. Many Shi’ites complain of being politically and economically marginalised, a charge the government denies.