The Afghan Taliban said on Monday that Kevin King, one of two professors from the American University of Afghanistan who were kidnapped in Kabul last year, is seriously ill and needs urgent medical attention.
Taliban spokesman Zabihullah Mujahid said King, an American, was suffering from "dangerous" heart disease and kidney problems.
"His illness has intensified, his feet have swollen and sometimes he becomes unconscious and his condition worsens every day," Mujahid said in a statement.
"We have tried to treat him time to time but we do not have medical facilities as we are in a war situation," he said.
The U.S. State Department called for the immediate and unconditional release of King and other hostages.
King and his Australian colleague, Timothy Weeks, were kidnapped in August 2016 as they were returning to their compound in the Afghan capital.
Afghan and Western officials believe the men are being held by the Haqqani network, a militant group affiliated with the Taliban that has carried out many other kidnappings. They acknowledge that an unsuccessful rescue attempt was made in eastern Afghanistan months after the two were taken.
The Taliban statement came around two weeks after Pakistani troops rescued Canadian Joshua Boyle and his American wife, Caitlan Coleman, from an area near the Afghan border. They had been held by the Haqqanis since being kidnapped in 2012.
Earlier this year, the Taliban released a video of King and Weeks showing them pleading with their governments to release Taliban prisoners in turn for their freedom.
Kidnapping high profile targets has become a lucrative business for the Taliban and other militant groups in Afghanistan who in return often demand huge ransom or release of their members.