Top Chinese banks have halted most dealings with North Korea, an unprecedented move to use financial leverage against Pyongyang that reflects Beijing’s exasperation with Kim Jong-eun’s regime.

The financial blockade against North Korea goes beyond what Beijing had agreed to implement in UN resolutions, with several leading banks saying they had stopped all cross-border cash transfers, regardless of the nature of the business. A UN resolution this year called only for sanctions in cases where money might contribute to North Korea’s missile programmes.

Nevertheless, the blockade is not watertight. A smaller bank based in northeast China said it was still handling large cross-border transfers, a sign Beijing is not cutting off North Korea. China is North Korea’s most important economic partner. Trade bet-ween the two has grown, providing a cash lifeline to the impoverished state.