Zainab al-Khawaja, who was arrested again for trying to see her father, Abdulhadi al-Khawaja, told CNN she had spoken with him Saturday night.
"There were very long pauses," she told CNN. "He was trying to breathe between every word."
Abdulhadi al-Khawaja is protesting the life sentence he received for his role in anti-government demonstrations that continue to roil his country. Sunday marked the 60th day of his hunger strike and the first anniversary of his arrest.
She said her father said he told guards that he would live with pride whether it was in or out of prison.
"His tone and the way he was speaking was like he was saying goodbye. We're not sure if we'll ever see him again," his daughter said.
She went Saturday to the military hospital where her father is being held. She had done the same Thursday night at the Interior Ministry where her father was previously held and was arrested for allegedly assaulting a public officer. She was later released.
Government spokesman Abdul-Aziz al-Khalifa said Sunday that the daughter was detained after she started "shouting her head off" and "being rude." She was charged with "disturbing the peace in a general hospital and insulting members of the security force here and all the guards in the hospital," he said.
As to the daughter's comments on how her father is being treated, the spokesman said he finds it "very hard to believe that the hospital staff would treat him that way." He said he had full faith in the staff and that her story is an "exaggeration."
Zainab al-Khawaja said security guards took her outside and tied her hands and legs to a wheelchair. She was taken to a military base and interrogated and again questioned at a police station.
She said she was charged with insulting an official and then released after signing a document saying she would appear at a public prosecution office when requested to do so.
The government spokesman declined to comment on how the guards may have detained her, or on her treatment.
Meanwhile Sunday, Bahraini authorities said they will not hand over Abdulhadi Al-Khawaja to Denmark as requested.
Bahrain's Supreme Judiciary Council said he did not meet the conditions stipulated in its criminal procedures law to hand over the accused to foreign countries, the Bahrain News Agency reported.
Al-Khawaja had lived once in Denmark and holds Danish citizenship.
Al-Khalifa said Saturday that Abdulhadi al-Khawaja was in stable condition and receiving "the utmost care that is available."
The Bahrain Center for Human Rights -- a group Abdulhadi al-Khawaja founded -- said he had recently threatened his guards that he would stop drinking water, in addition to continuing his hunger strike, unless his treatment improved.
Records showed that al-Khawaja had lost about 10 kilograms (22 pounds) and had a low hemoglobin level, though not critically low, the government said. He was also reportedly taking fluids, mineral supplements, glucose and juice on a daily basis.
Al-Khawaja was arrested in April 2011 for his role in anti-government protests that began a month earlier with demands for political reform and greater freedoms in the Sunni-ruled, Shiite-majority nation.
Opposition groups say more than 1,000 people -- mainly Shiites -- were detained for allegedly taking part.
In June, Bahrain found Abdulhadi al-Khawaja and seven other Shiite opposition activists guilty of plotting to overthrow the country's Sunni royal family.
In November, an independent inquiry commissioned by the king confirmed that security forces had tortured and used excessive force against civilians arrested during the crackdown and that thousands of workers were allegedly fired for participating in the protests.
Since then, demonstrators and police have continued to clash.
Abdulhadi al-Khawaja can appeal his life sentence during a hearing April 23, the government said.
