A leading member of Bahrain's main Shia opposition party has been arrested.
Khalil Marzook, assistant secretary general of Wefaq, was summoned to a police station on Tuesday for questioning over a speech he made last week, one activist said.
Mr Marzook was then arrested on charges of inciting youth violence and trying to overthrow the government, he added.
Wefaq said it considered the move an escalation in the government's campaign to suppress dissent in the kingdom.
Mr Marzook is a former deputy speaker of parliament, who resigned along with other Wefaq MPs when the government launched a deadly crackdown on pro-democracy demonstrations in February 2011.
The protesters were demanding more rights and an end to discrimination against the majority Shia community by the Sunni royal family.
In a statement, Wefaq said its general secretariat had held an extraordinary meeting to discuss the "regime's recklessness" following Mr Marzook's arrest.
The party claimed the authorities were targeting political opponents as part of an effort to heighten the unrest in the Gulf island state.
It also alleged that Mr Marzook's arrest was a reaction to a resolution passed by the European Parliament on Thursday that called on the Bahraini authorities to stop using violence against peaceful protesters and to allow an independent investigation into alleged human rights abuses, particularly those involving children.
"The prosecution, detention and torture of protestors must stop and freedom of expression and assembly, both online and offline, must be guaranteed," the resolution stated.
MEPs also criticised the EU for its "lack of response" to the crackdown.