Hundreds of thousands of building workers in Pyongyang are being put under intense pressure to complete apartment blocks before harsh weather sets in. "Project managers are now openly providing drugs to construction workers so that they will work faster," a Pyongyang source in construction told Radio Free Asia. "[They] are undergoing terrible sufferings in their work."

The only recourse for dissent in the highly controlled state by dissenting workers is daubing graffiti and slogans on the walls, which allude to the taking of crystal meth – "Pyongyang speed is drug speed" – while others have called the construction workers "drug troops".

The graffiti was scrawled at the site of an unfinished building and is being viewed as a political offence by North Korean authorities, with police officials seeking out those who wrote the comments, according to a source in North Jagang province. "Investigators are warning construction workers that they will be severely punished for further incidents of this kind," the source told Radio Free Asia, which is funded by the US government.

A construction drive is underway in North Korea which includes a 70-story high-rise apartment at least 60 other structures and other public buildings in Pyongyang. The Ryugyong Hotel, nicknamed the "Hotel of Doom" has still not been completed, even though it was due to have been finished in 2013. Nevertheless, The North Korean government have proclaimed this a "great golden age of construction".

Working conditions in Asia have been likened to slave labour and human rights organisations are calling on the UN to take action against Kim Jong-un.

Phil Robertson, Asia director for Human Rights Watch, told the Telegraph: "It's going to be hard to verify that this is happening, but if it is confirmed then we utterly condemned it.

"The real issue here is slave labour, and our immediate reaction to this was that if they want faster workers why not actually pay them, instead of resorting to giving them drugs?

"The North Korean government wants to finish these buildings to somehow prove that they are a developed country. But this kind of forced labour has been unilaterally condemned by the international community."