Samjiyon is one of Kim’s signature economic projects, but was delayed by shortage of building materials and labour.

North Korean leader Kim Jong Un has celebrated the completion of his signature construction project, a new city near the sacred mountain where his family claims its roots, with state media on Tuesday calling it the “epitome of modern civilisation”.

A large celebration involving fireworks was held at the city near Mount Paektu on Monday, the official KCNA news agency said. The Rodong Sinmun, a governing party mouthpiece, ran photos showing Kim smiling as he cut a ribbon at the ceremony amid buildings covered in snow.

The city, named Samjiyon, is envisaged as a “socialist utopia” with new apartments, hotels, a ski resort and commercial, cultural and medical facilities.

KCNA said it could accommodate 4,000 families and has 380 blocks of public and industrial buildings in “hundreds of hectares”.

The city is one of the largest economic initiatives Kim has launched as part of his drive for a “self-reliant economy”, but its construction was delayed chiefly due to shortages in building materials and labour as a result of sanctions imposed to curb Pyongyang’s nuclear programme.

Delays in construction prompted the Kim regime to mobilise youth labour brigades, which defectors and human rights activists likened to “slave labour” as they get no pay, poor food and are forced to work more than 12 hours a day for up to 10 years in return for better chances to enter a university or join the all-powerful Workers’ Party of Korea.