Belgrade - Serbia plans to raise the question of the responsibility both of Ukraine and Russia for the crippling gas crisis, the head of national supplier Srbijagas, Dusan Bajatovic, said Thursday.

"We will ask for explanations from the Russian Jugorosgas and Gazprom, as well as the Ukrainian Naftogaz and if we find any of them unacceptable, we will raise the question of responsibility," Bajatovic told radio B92.

Jugorosgas is a majority Russian joint venture with Serbian partners with the monopoly right to supply Russian gas.

A lawsuit against Ukraine was already being prepared in Serbia, Bajatovic said. He said there was no "legal and economic ground" for proceedings against Russia.

He stressed that there were no political motives behind the decision to launch lawsuits against Kiev and not against Moscow, Belgrade's close political and economic ally.

"It is not a political problem for us to sue Russia. There was gas on the Ukrainian and Hungarian border until a few days ago, then the Ukrainians twisted the taps shut," Bajatovic said.

Serbia was caught out without any gas reserves whatsoever when the row between Russia and Ukraine led to the closing of pipelines last week.

Hundreds of thousands of homes were left without heating amid a spell of freezing weather and the industry had to shut down.

Belgrade was forced to arrange expensive emergency supplies from Germany and Hungary only to keep the priority consumers, such as remote heating plants, running.

The current emergency arrangement runs until January 20. (dpa)