The two professors of the American University of Afghanistan were kidnapped last August.
The two professors of the American University of Afghanistan were kidnapped last August and appeared in a Taliban hostage video in January, the first proof that they were alive.
"The American University of Afghanistan appeals for the immediate and unconditional release of our friends and colleagues, Kevin King (American) and Timothy Weeks (Australian)," the university said.
"Kevin and Tim are innocents. Both came here to teach young Afghans, helping them to contribute to the rebuilding efforts of Afghanistan."
President Ashraf Ghani is expected to approve the execution of 11 Taliban and Haqqani Network prisoners, a government source told AFP, in apparent retaliation to a catastrophic truck bombing on Wednesday.
Afghanistan's intelligence agency has blamed the Taliban-allied Haqqani Network for the attack in Kabul's diplomatic quarter that left 90 people dead and more than 400 wounded.
The Taliban -- currently in the midst of their annual "spring offensive" -- have denied that they were involved.
The Taliban have threatened "harsh exemplary attacks" in a statement on their website, including the killing of foreign hostages it holds if the government executed the 11 prisoners.
The Taliban also hold Canadian Joshua Boyle and his American wife Caitlan Coleman, who had two sons in captivity after being kidnapped in Afghanistan in 2012 during a backpacking trip.
The Haqqani Network, long thought to have ties to neighbouring Pakistan's shadowy military establishment, is led by Sirajuddin Haqqani -- who is also the Taliban's deputy leader.
It has carried out numerous attacks in Kabul, including the 2008 Indian embassy bombing that killed almost 60 people.
Public anger has mounted in Kabul after Wednesday's attack, the deadliest in the city since 2001, which was launched from an explosives-laden sewage tanker that tore a massive crater in the ground.
Protesters have demanded the execution of Anas Haqqani, son of the Haqqani network's founder, who has been held by the Afghan government since 2014.
But a government source told AFP that Anas was not among the 11 prisoners the government planned to execute.