About 1,300 animals in a Bulgarian zoo were left without gas to heat their enclosures today, the latest victims of the Russia-Ukraine supply row.

The zoo in the capital Sofia rushed to switch to electric heaters to keep its elephants, monkeys, parrots, rhinos and hippos warm in the sub-zero temperatures.

"About a third of the animals are vulnerable to cold," said the zoo's director Ivan Ivanov said. "Only the Siberian tigers feel comfortable in these temperatures."

All Russian gas supplies to Europe were halted over a price dispute a day earlier.

Heating was sharply reduced in snow-covered Sofia and hundreds of thousands of people across the Balkans were left in the cold as the impact on the hardest-hit region grew.

Bulgaria and the western Balkans rely almost entirely on Russian gas supplies which are crucial in the winter because utilities use gas to heat homes, offices and factories.