Many Bulgarians only realised that Russia was the country’s exclusive supplier of natural gas last January when temperatures in their homes fell sharply and hot water taps ran cold. The dispute between Russia and Ukraine shut down the pipeline bringing gas across the Danube from Romania and forced heating plants in Bulgarian cities to operate at minimum capacity during the coldest winter in a decade.

Bulgaria’s big chemicals and fertiliser plants were also hard hit. Industrial output fell by almost 20 per cent in the first two months.