Slovakia, which depends on Russia for all its gas, has declared a state of emergency, forcing big energy users to cut consumption-including its flagship foreign carmakers.

As a report commissioned by the US Department of energy shows, an emergency programme to replace current energy supplies or equipment to anticipate peak oil would need about 20 years to take effect.

Other nuclear plants across the country have been shut down for emergency safety tests over the summer, usually the time of peak energy demand in Japan due to the heat and humidity.