A corruption investigation and a high-level resignation are threatening to plunge Ukraine’s central bank into turmoil, undermining Kiev’s ability to stabilise its currency and pull out of a deep recession.

Oleksandr Savchenko, deputy head of Ukraine’s National Bank, the central bank, resigned on Friday, accusing colleagues of pursuing failed monetary policies and of co-conspiring in “currency speculation” deals that broke trust in Ukraine’s hryvnia, causing it to plunge more than 10 per cent in recent weeks.