The daughter of Abdulhadi al-Khawaja, a well-known human rights activists in Bahrain, has been transferred to prison after being arrested at a protest against her father's detention.
Zainab al-Khawaja reportedly started a protest in front of the interior ministry in the Gulf kingdom's capital on Thursday night, demanding the release of her father who has been on hunger strike for nearly two months.
The Bahrain Centre for Human Rights, an organisation co-founded by the elder Al-Khawaja, reported that police had tried to move Zainab away from the ministry building, and fired tear gas at other activists who were gathered with her.
She was then arrested and the road leading to the ministry was closed, the centre reported.
Al-Khawaja began his hunger strike on February 8 to protest his own detention and that of several other activists arrested last April.
He and six other opposition figures were given life sentences by a military court in what Bahraini and international human rights groups have called an unfair trial.
Khadija Almousawi, Al-Khawaja's wife, tweeted on Friday morning that her husband's health had "deteriorated" and that he had been moved to a military hospital for treatment.
His declining health has brought international appeals for intervention, most recently from Physicians for Human Rights (PHR).
PHR called on the government to "release Al-Khawaja, allow an impartial investigation of allegations of torture and ill-treatment during his detention, and hold all perpetrators of torture accountable for their actions".
Al-Khawaja is also a citizen of Denmark, where he lived in exile for decades, returning to Bahrain after the government announced a general amnesty in 2001.
Officials in Denmark say they have called for him to receive medical treatment outside Bahrain.
Al-Khawaja is not the first prisoner to go on hunger strike in Bahrain since widespread unrest began in February 2011.
Mahdi Abu Deeb, the head of Bahrain's teachers society, went on a three-week hunger strike to protest his detention. But activists say Al-Khawaja's is the first open-ended hunger strike in Bahrain.
Meanwhile, protests against the upcoming Bahrain Formula One race continued across the island nation, with protesters burning tyres on main roads in the capital Manama on Thursday night.