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.