Pardoned by King Hamad in 2015 after serving three months of a six-months jail sentence

Freed in May 2014 after serving a two-year jail sentence for his role in the 2011 protests

One of the leaders of the Bahraini uprising of 2011

Bahraini police have arrested a prominent activist during a raid on his home early on Monday, rights groups and his family said, part of a wide crackdown on dissent more than five years after the Arab uprising.

It was not immediately clear why authorities arrested Nabeel Rajab, president of the Bahrain Centre for Human Rights.

However, his arrest comes after Zainab al-Khawaja, another prominent activist, fled the Gulf 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.

Bahraini officials could not be immediately reached for comment.

Rajab helped lead protests during Bahrain's 2011 demonstrations as the island's majority Shia population and others demanded more political freedom 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.

READ MORE: Bahrain frees dissident Nabeel Rajab for health reasons

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 has been detained by authorities several times.

In 2015, King Hamad bin Isa Al Khalifa pardoned Rajab over health concerns following imprisonment for three months on charges related to comments he made online criticising the treatment of political prisoners at a prison in the country.

READ MORE: Bahrain five years after the protests

Rajab at the time also faced a six-month sentence for insulting defence and interior ministries on Twitter, when he alleged that Bahrain's security institutions were incubators for hardline ideology after several former members of the country's security service apparently joined Islamic State of Iraq and the Levant (ISIL).

Brian Dooley, director of the Washington-based group Human Rights First, said Rajab's detention appeared timed to come before a planned United Nations meeting on human rights. He said other activists were prevented from leaving Bahrain to attend the conference in Geneva.

"Nabeel's arrest is a forceful, frightening message from the Bahraini government that it is moving against even activists with strong international connections," Dooley said in a statement.