Friends of Canadian pastor Hyeon Soo Lim have condemned his sentencing to a life of hard labor in North Korea as "outrageously unjust", as he spent many years providing humanitarian aid to the impoverished country.

Speaking to the Daily NK, a friend of Pastor Lim and defector from North Korea said he knew the 60-year-old pastor in Canada and would go on trips with him, attend his sermons and support his work.

"He really helped people like me who are from North Korea a lot. In some ways, I would say a lot of people from the North managed to get permanent residency in Canada thanks to his help. He provided a lot of financial help but also supported us so we would be able to settle down quickly in Canada. Defectors who were able to get permanent residency thanks to Pastor Lim now have stable lives in Canada."

As reported by the Gospel Herald, Lim had been doing humanitarian work in North Korea since 1997 and had visited the isolated country more than 100 times, according to his Toronto church, the 3,000-member Light Korean Presbyterian Church.

North Korea's highest court said Lim had attempted to overthrow the government and undermine its social system with "religious activities" for the past 18 years, China's official Xinhua news agency reported. At the time of his capture, the pastor had a "very serious health problem, very high blood pressure", his church said.

In continuing his comments to the news outlet, the source revealed that Lim cared very little about material things; he had lived in the same apartment for 25 years and had an old Korean car.

"In North America, if you have a church with over 3,000 members in the congregation, it's considered a huge church. I don't know how this will sound, but had he wanted to, he would have been able to live a comfortable life in Canada, but he didn't choose to live that way at all," the source explained.

"He would go to the North two to three times a month. All combined, I think he has visited more than 100 times," the source added.

The pastor's work there included building a bread factory in the Rajin-Sonbong area, a service to help North Korea's homeless children who often beg for food, a noodle factory, and regularly sent aid from Canada.

Because of his devotion to helping the people of North Korea, people were shocked when Pastor Lim was arrested, the source said. "He went there not for any political reasons but because he wanted to help the North Korean people."

They feared the worst when he did not return home. "North Korea easily can hold someone captive or kill them if they think that person doesn't suit their taste. That had become reality."

During a recent interview with CNN, the pastor revealed that he works eight hours a day, six days a week, with rest breaks, digging holes for the planting of apple trees in the prison orchard. Thus far, he has not seen any other prisoners, and is not allowed contact with the outside world.

"I wasn't originally a laborer, so the labour was hard at first," Lim said in Korean through an interpreter. "But now I've gotten used to it."

Despite his bleak circumstances, the pastor revealed that he continues to pray for the unification of North and South Korea, and that no one will ever have to suffer through the same experience he has.

"I hope I can go home someday," Lim said. "Nobody knows if I will ever go home, but that is my hope. I miss my family. I am longing to see them again, and my congregation."