The Canadian man rescued from the Taliban after being held for five years thought his captors were playing a joke on him when they said Donald Trump was president of the United States.

Joshua Boyle, his American wife Caitlan Coleman were kidnapped and held hostage by a Taliban-linked extremist network for five years.

The couple's three children - two boys and a baby girl - were born in captivity.

According to Boyle, the family were rarely given any information about the outside world.

But when he was forced to participate in a 'proof of life' video, he was informed Donald Trump had been elected president.

Boyle told the Toronto Star he thought his captor was making a joke.

"It didn't enter my mind that he was being serious," he said.

In a separate interview, Boyle revealed why he and his wife decided to have children with being held captive, saying they had always planned to have a big family and decided, "Hey, let's make the best of this and at least go home with a larger start on our dream family."

"We always wanted as many as possible, and we didn't want to waste time. Cait's in her 30s, the clock is ticking," Boyle told AP.

Boyle said the kids are now 4, 2 and "somewhere around 6 months."

"Honestly we've always planned to have a family of 5, 10, 12 children ... We're Irish, haha," he wrote.

Coleman, 31, and Boyle, 34, were kidnapped in Afghanistan in October 2012 during a backpacking trip through Central Asia. On Friday, Boyle said they travelled to the country as "pilgrims" to help people in need in a Taliban-controlled region.

Boyle said he knows there will be many more questions about the family's captivity and rescue, and he plans to address them in coming days, already fielding an inbox full of emails from media outlets around the world.