Besides the deaths, hundreds have been detained and tried in secret at a special security court. Dozens have been convicted of anti-state crimes.
Eight prominent opposition figures have been sentenced to life in prison on charges of trying to overthrow the state, including rights activist Abdulhadi al-Khawaja, whose two-month and counting hunger strike has galvanized the Shiite resistance in the past weeks.
Shiites account for about 70 percent of Bahrain's population of just over half a million people, but claim they face widespread discrimination and lack opportunities granted to the Sunni minority. The country's leaders have offered some reforms, but the opposition says they fall short of Shiite demands for a greater voice in the country's affairs and an elected government.
The unrest has put Washington into an awkward position. U.S. officials have called for efforts to reopen political dialogue in Bahrain, but are careful not to press too hard against the nation's leadership and possibly jeopardize its important military ties.
Associated Press writer Barbara Surk in Dubai, United Arab Emirates contributed to this report.