The prominent Bahrain human rights activist and critic of the ruling family, Maryam al-Khawaja, has been arrested by authorities on her arrival at the Gulf state's airport.
Posts on the Twitter account of Khawaja said she had been charged with insulting the king, assaulting police officers, and faced charges for her involvement with the rights campaign, Wanted For Justice.
Khawaja, the co-director of the Gulf Centre for Human Rights, is the daughter of Shia Muslim activist Abdulhadi Abdulla Hubail al-Khawaja, who has been in custody in Bahrain since 2011 and is on hunger strike.
The Reuters news agency reported her mother Khadija al-Musawi as saying her daughter would be transferred to the public prosecution court on Sunday.
A later post on her Twitter account stated that she would be held for seven days and was not allowed to see a lawyer before her interrogation.
Khawaja, who has lived abroad for several years, had returned to Bahrain to see her father, who recently decided to go on a new hunger strike. Her sister, Zainab, had been released from custody on Friday pending further investigation.
Bahraini authorities were not immediately available to comment.
Bahrain has experienced heavy political instability since protests led by Shia Muslims erupted in 2011 after similar unrest in Egypt and Tunisia.
Shia, who make up the majority of Bahrain's population, complain of political and economic marginalisation, an accusation the government denies.
In July, Bahrain declared US Assistant Secretary of State for Democracy, Human Rights and Labour Tom Malinowski, persona non grata after he met opposition figures in the kingdom.
Under criticism from human rights groups, the government invited an independent inquiry to examine its handling of the trouble in 2011. Its report said the authorities had used widespread and excessive force, including torture.
The Bahraini government says it has taken steps to address the problems by dismissing those responsible and introducing cameras at police stations.