North Korea's black economy, which is believed to have grown as a market force in recent years, helped the isolated country weather international sanctions last year, according to a researcher at South Korea's state-run think tank on Sunday.

North Korea, which has been under layers of international sanctions over its nuclear weapons and missile program, is expected to focus on stimulating its domestic consumption this year, said Lee Jong-kyu, a researcher at the Korean Development Institute, in a recent report.

Last year, North Korea mobilized its people for large-scale construction projects under the "70-day" and "200-day" campaigns.

Lee said North Korea had no choice but to press its own people to navigate themselves through the economic hardship as international sanctions strengthened.