It wasn't immediately clear why authorities detained Nabeel Rajab, the president of the Bahrain Center for Human Rights. However, his detention comes after Zainab al-Khawaja, another prominent activist, fled the island nation for Denmark in recent days over fears of being imprisoned again.
Police seized electronic devices and other items from Rajab's home as they detained him, according to the Bahrain Institute for Rights and Democracy. Rajab's wife, Sumayia, also confirmed his arrest and said on Twitter that their home was searched.
Rajab helped lead protests during Bahrain's 2011 demonstrations as the island's majority Shiite population and others demanded more political freedoms from its Sunni rulers.
Bahrain, home to the US Navy's 5th Fleet, crushed the protests with the help of troops from Saudi Arabia and the United Arab Emirates.
In the time since, the island has faced low-level unrest, protests and attacks on police. Other prominent opposition figures and human-rights activists remain imprisoned, while some have had their citizenship stripped by the government and been deported.
Rajab at the time also faced a six-month sentence for insulting defense and interior ministries on Twitter when he alleged that Bahrain's security institutions were incubators for extremist ideology after several former members of the country's security service apparently joined the extremist Islamic State group.
Brian Dooley, director of the Washington-based group Human Rights First, said Rajab's detention appeared timed to come ahead of a planned United Nations meeting on human rights. He said other activists were prevented from leaving Bahrain to attend the conference in Geneva.
