(CNN) -- A global human rights organization Tuesday called on Bahraini authorities to release a jailed activist who's in poor health after a more than two-month hunger strike.
Amnesty International asked for the immediate and unconditional release of Abdulhadi al-Khawaja, 52, saying in a statement that Bahrain's "determination to persecute him seems to override any consideration for justice or humanity."
The group believes his "health is rapidly deteriorating" due to his hunger strike -- which enters its 62nd day Tuesday -- and said it would "hold the Bahraini authorities responsible for his situation."
Amnesty's statement said al-Khawaja and 13 other prominent opposition activists are being being held "solely for peacefully exercising their rights to freedom of expression and assembly."
The men have not advocated any violence, said Amnesty.
Bahraini government officials said Tuesday that a medical checkup by two independent experts revealed al-Khawaja is not critically ill.
He is taking fluids orally and intravenously, and is in good condition, said Abdulaziz Al Khalifa, a spokesman for the internal affairs authority.
Al-Khawaja was arrested a year ago and is serving a life sentence for his role in anti-government protests that continue to roil Bahrain.
The United Nations has urged Bahrain to consider transferring the detainee, who holds Danish citizenship, to Denmark on humanitarian grounds.
"In cases where there is a hunger strike, the health and well-being of the person should be the foremost concern," United Nations spokesman Martin Nesirky said Monday.
Relatives are concerned about his health. His daughter said al-Khawaja is having trouble breathing and is harassed by hospital staff and security guards.
"There were very long pauses," Zainab al-Khawaja said Sunday after speaking with her father. "He was trying to breathe between every word."
"His tone and the way he was speaking was like he was saying goodbye," she said. "We're not sure if we'll ever see him again."
Al-Khawaja's wife told Amnesty International that he had been barred from receiving visits for the past four days.
"At the very least, the authorities must immediately allow Abdulhadi al-Khawaja's family and lawyer to visit him," Amnesty's statement said.
In a letter to U.S. President Barack Obama Monday, Amnesty and 14 other rights organizations urged Obama to demand Bahrain release him.
"The evidence is clear that al-Khawaja and others were sentenced in violation of their rights to freedom of expression, assembly and association, which are protected under international law," the groups wrote.
A judicial panel has said al-Khawaja does not meet the conditions to be transferred into the custody of Denmark, according to the Bahrain News Agency.
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.
In June, Bahrain found him and seven other Shiite opposition activists guilty of plotting to overthrow the country's Sunni royal family.
He can appeal his life sentence during a hearing April 23, the government said.
CNN's Samira Said contributed to this report