By Alex Jensen

SEOUL

North Korea’s economy shrank 3.5 percent in 2017, according to Seoul’s Bank of Korea (BOK) on Friday.

It means the North slumped to its poorest performance since 1997 when the country was in the grip of a deadly famine.

Moreover, the decline represented a turnaround from North Korea’s 3.9 percent economic expansion in 2016.

South Korea’s central bank explained the data by pointing to tougher sanctions imposed by the U.N. Security Council as well as drought.

“The negative growth is attributable to a drop in its mining output and a retreat in its heavy and chemical industries, as the United Nations imposed tougher sanctions over its nuclear and missile activities," a BOK official said in comments carried by South Korea’s Yonhap News Agency.

When new sanctions were introduced last year to curb North Korea’s development of nukes, the country’s revenue sources were squeezed.

It was banned from exporting coal among other mineral resources.

The BOK’s report also highlighted the gap between the Koreas, with the North’s gross national income (GNI) standing at 36.6 trillion won (US$32.3 billion) last year, which was just 2.1 percent of the South’s GNI.

Seoul has made it clear that sanctions will remain in force against North Korea until it completely denuclearizes.