Several North Korean oil tankers which typically pick up oil products from China have not recently broadcast their locations, while others appear to be waiting outside Chinese ports, analysis of data from vessel tracking site Marine Traffic shows.

The news comes amid reports from the North Korean capital – and the northeastern province of Rason – of a sudden surge in civilian prices for gasoline, an indication that supplies may have become more limited.

The spiking prices – which jumped 83 percent – also follow reports in Chinese media that restrictions on the DPRK’s oil flows were under consideration