UPDATE 1-Gas row leaves thousands shivering in Balkan cold

(Recasts with other Balkan countries, details)

By Anna Mudeva and Maja Zuvela

SOFIA/SARAJEVO, Jan 7 (Reuters) - Thousands of Bulgarians, Bosnians and Serbs were left in the cold and some companies and schools did not operate on Wednesday after Russian gas supplies were halted to southeastern Europe.

The disruption in Bosnia brought back bitter memories of the 1992-95 conflict when heating was often off in winter.

"It all reminds me of the war when we were freezing, except there is no shooting," said Hilmo Celjo, who stood in a queue on the outskirts of Sarajevo to buy wood and coal.

The western Balkans and Bulgaria, the poorest European Union nation, were among the worst hit by a cut in Russian gas supplies to Europe via Ukraine over a price row.

They have no access to alternative routes and rely almost entirely on Russian gas, which stopped flowing to Europe via Ukraine completely on Wednesday after dwindling since Jan 1.

At least 45,000 households in Bulgaria were without central heating on Wednesday as utilities needed time to switch to alternative fuels, municipal officials said.

Dozens of schools and kindergartens were closed in the Balkan country of 7.6 million people.

Close to 76,000 households in Bosnia's capital Sarajevo and over 3,000 in the eastern town of Zvornik, were left shivering.

Shops in Sarajevo ran out of electric heaters after residents rushed in panic to secure alternatives as temperatures hit minus 15 degrees overnight.

In Serbia, officials said they had no more reserves and that tens of thousands of people had lost heating when most were at home to celebrate Orthodox Christmas.

Serbia's second largest city Novi Sad, where a third of the more than 200,000 population rely on natural gas for heating, were unable to convert to other fuels, said Milan Budimir, a spokesman for the energy ministry.

STEELMAKERS SHUT

"This is an absurd situation for the 21st century," Bulgaria's Economy and Energy Minister Petar Dimitrov told national broadcaster bTV. "Russia and Ukraine must find a quick solution ... as the economies of half of Europe are at risk."