North Korea on Thursday wrapped up a 200-day mass mobilisation campaign aimed at boosting an economy struggling with upgraded UN sanctions imposed after its two nuclear tests this year.

Coming hard on the heels of a similar 70-day campaign that ended in May, the 200-day version kicked off in early June, pushing extra hours and working weekends.

On the final day Thursday, as on every day for the entirety of the campaign, dozens of female propaganda troupes armed with drums and flags put on early morning performances at strategic locations across the city, encouraging commuters on their way to work.

A large placard erected in front of each troupe - and replicated in work units across the country - asked the question: "Comrade, have you carried out your battle plan today?"

On Thursday the section on the placard counting down to the end of the campaign read: "Days remaining - 1"

Outside experts say the economic benefits of such campaigns are dubious at best, with some suggesting they have a negative net impact on productivity as exhaustion fuels inefficiency.

New York-based Human Rights Watch has condemned them as mass exercises in "forced labour" that use political coercion to extract economic gain.

North Koreans are used to mandatory mass mobilisation campaigns, with participation rigorously monitored and used as a measurement of loyalty to the regime.

But Andrei Lankov, a veteran North Korea watcher and professor at Kookmin University in Seoul, said the modern-day campaigns were more show than substance -- a strategy from a bygone socialist era that was long past its sell-by date.

The primary focus is on industrial output, with top priority given to reducing a yawning energy deficit that acts as a constantly tripping circuit breaker on economic growth.

Power outages remain commonplace in Pyongyang which, as the country's showcase capital, receives privileged utilities supplies.

Heavy batteries and power-saving LED lights are popular items in markets for those who can afford them, while the balconies of Pyongyang's apartment blocks bristle with solar panels to keep basic household appliances running.

The current 200-day campaign was launched to kick-start a new five-year economic plan unveiled by supreme leader Kim Jong-Un at a ruling party congress in May.

The plan was long on ambition but short on detail, offering no clear hint of reform despite Kim's call to "expand our method of economic management".

According to South Korea's central bank, the North Korean economy contracted by 1.1 percent last year -- the first downturn since 2010.

Given the paucity of economic data released by the North, estimating its GDP is a hazardous exercise, but experts say upgraded sanctions are clearly posing a challenge that old-school, mass mobilisation campaigns are simply no match for.

North Korea carried out two nuclear tests this year, in January and September, drawing two separate rounds of UN sanctions aimed at blocking Pyongyang's access to hard currency revenues.

The latest measures included a cap on North Korea's coal exports -- a key foreign exchange earner.