A Bahraini administrative court on Sunday ordered the dissolution of the country's largest opposition group, the Shiite al-Wefaq National Islamic Society.
The ruling in Manama comes amid an increasing crackdown on opposition figures in the Sunni-led, Shiite-majority Gulf monarchy, which in 2011 crushed a widescale pro-democracy protest movement.
Al-Wefaq was shut down last month under an emergency court order after the Justice Ministry accused the group of undermining the state, spreading sectarianism and being linked to terrorist activities.
Lawyers for Al-Wefaq said they had not yet decided whether to appeal Sunday's ruling.
They had withdrawn from the case after the judge refused their request to access the party offices to obtain documents they said they needed to mount a defence.
The ruling came a day after authorities said they planned to prosecute Bahrain's top Shiite religious figure, 79-year-old Ayatollah Isa Qassim, for alleged illegal fundraising and money laundering.
Qassim, seen as the spiritual leader of al-Wefaq, was stripped of his citizenship last month, angering supporters who have mounted a sit-in outside his home in a village north of the capital Manama, fearing his deportation or arrest.
Al-Wefaq's political leader, Sheikh Ali Salman, was sentenced in May to nine years in prison on charges including attempting to overthrow the regime and inciting sectarian hatred.
The accelerating crackdown has led the UN human rights office to call for the release of Bahraini political prisoners, while UN chief Ban Ki-moon has expressed concern over restrictions on the opposition and moves against human rights activists.
The United States "is deeply concerned" by Sunday's court decision, Secretary of State John Kerry said in Washington, calling it "the latest in a series of disconcerting steps in Bahrain."
He noted that the government previously tried to reach out to the opposition, which boycotted parliamentary elections in 2014.
"However, the government's recent steps to suppress nonviolent opposition only undermine Bahrain's cohesion and security, as well as the region's stability," Kerry said. "These actions are inconsistent with US interests and strain our partnership with Bahrain. They also contradict the government's stated commitments to protecting human rights and achieving reconciliation with all of Bahrain's communities."
He called for the government to reverse "these and other recent measures."