An Australian man who spent three years in Taliban captivity said Sunday that he believes US special forces tried to rescue him and an American colleague on half-a-dozen-occasions.

Speaking in Sydney for the first time since he was freed in a prisoner swap deal, 50-year-old Timothy Weeks said he never lost hope, but the captivity "had a profound and unimaginable effect" on him.

Detailing a hellish life spent moving between windowless cells in Afghanistan and Pakistan Weeks said "after almost 1,200 days, our ordeal ended as abruptly as it had begun."

Weeks and American colleague Kevin King were freed on November 20 as part of deal between the Taliban, US, Australian and Afghan governments.

The pair - both professors at the American University in Kabul - were kidnapped by gunmen wearing military uniforms as they returned home from classes in August 2016.

"I struggle to find words to express just how completely this has changed me. At times, I felt as if my death was imminent, and that I would never return to see those that I loved again," he said.

"But, by the will of God, I am here, I am alive and I am safe."

He recalled that in April this year he was woken "at around 2:00am and we were taken down into the tunnels."

He was told at the time that it was the Islamic State group's local affiliate. "I believe now that it was the Navy SEALs coming in to get us. And the moment that we got into the tunnels, we were just one or two metres underground. There was a huge bang at the front door."

"Our guards went up and there was a lot of machine-gun fire," he said. "I believe it was the Navy SEALs right outside our door. I think they came in six times to try to get us. And that a number of times they missed us only by hours."

Copyright Agence France-Presse, 2019