Russia’s Gazprom threatened on Thursday to cut off a quarter of Ukraine’s gas supplies within days over non-payment of debts, as another possible energy stand-off between the nations loomed.

Speaking on Russia’s Vesti television channel, Sergei Kupriyanov, a spokesman for the state-owned energy group, said debt for gas supplied to Ukraine last month had swollen by $500m (€346m, £258m), bringing the total overdue to $1.5bn.