Police action was necessary to pull Bahrain back from the "brink of a sectarian abyss," the Gulf Arab state's Foreign Minister Sheikh Khaled bin Ahmed al-Khalifa said on Thursday.
Three people were killed and 231 wounded when police attacked anti-government protesters. The clashes came after thousands of overwhelmingly Shi'ite protesters took to Bahrain's streets demanding more say in the running of the kingdom.
After riot police had cleared protesters from Pearl square before dawn, soldiers in at least 40 trucks and armored vehicles took control of the road junction demonstrators had tried to turn into a protest base like Cairo's Tahrir Square.
The government should be elected by the people who would have the right to hold it accountable 
The crackdown by the Bahraini authorities appeared designed to snuff out the protests before they could gather momentum, unlike the sustained unrest that unseated Egypt's Hosni Mubarak.
The main Shiite bloc Wefaq, which holds 17 of parliament's 40 seats, announced withdrawing from the parliament in protest. "We feel there was a decision to hurt people," MP Ibrahim Mattar said.
Abdul Jalil Khalil, who heads Wefaq's bloc in parliament, said his group and six others had demanded that the government resign and make way for a new national unity government.
"This is an atrocity," he said of the bloodshed. "Whoever took the decision to attack the protest was aiming to kill."
Al-Wefaq, or the Islamic National Accord Association, has said it would not end its boycott until demands are met to transform Bahrain "into a constitutional monarchy where the people would be the main source of power."
"The government should be elected by the people who would have the right to hold it accountable," its secretary-general Sheikh Ali Salman said on Wednesday.
A 2001 referendum transformed Bahrain from an emirate into a constitutional monarchy and led to elections in 2002 for the first time since parliament was scrapped in 1975.
The prime minister is named by the king, while the opposition wants the premier to be elected.
International reaction
U.S. Secretary of State Clinton telephoned her Bahraini counterpart and “expressed deep concern about recent events and urged restraint moving forward. They discussed political and economic reform efforts to respond to the citizens of Bahrain," a senior State Department official, speaking on condition of anonymity, said.
The Pentagon called Bahrain an important partner but also urged restraint. "As a long-time ally and home to the U.S. Navy's Fifth Fleet, Bahrain is an important partner and the Department is closely watching developments there," Pentagon spokesman Col. Dave Lapan said. "We also call on all parties to exercise restraint and refrain from violence."
Secretary-General Ban said, "The reports from Bahrain overnight are deeply troubling," adding that he was disturbed by the violent methods being used to disperse demonstrators.
France and UK have also expressed concern at the crackdown on protesters and urgent Bahrain’s authorities to exercise restraint.