Bulgarian Prime Minister Sergei Stanishev will make an urgent visit to Moscow to discuss the current gas crisis, which has left Bulgaria without any supplies after Russia's cabinet ordered the shutdown of all gas deliveries through pipelines over Ukrainian soil because of a pricing dispute.

Russian prime minister Vladimir Putin has called his Bulgarian counterpart on January 13 to tell him that deliveries, agreed a day earlier, were resumed but did not get through Ukraine, the press service of the Russian government said in a statement.

Russia's cabinet, and not the presidency, formally controls state monopoly Gazprom, with a deputy prime minister acting as chairperson of the board since the Russian state raised its stake back to more than 50 per cent.

"A preliminary agreement on an urgent visit by Sergei Stanishev to Moscow has been made," the press service of the Russian cabinet said in a statement, without providing additional details.

The press service of the Bulgarian Cabinet did not formally confirm the news, but reports in Bulgarian media claimed that Stanishev would travel on January 14, accompanied by Economy and Energy Minister Petar Dimitrov, Deputy Economy Minister Galina Tosheva, who is also the interim head of the Bulgarian Energy Holding, of which state gas distribution firm Bulgargas is a subsidiary, and the Bulgarian ambassador to Moscow Plamen Grozdanov.

Bulgarian experts that would act as independent monitors of the gas deliveries will also travel to Moscow as part of the Government delegation.

The presence of international monitors has been agreed on January 12 as part of the memorandum that would result in Gazprom resuming deliveries to European Union countries early on January 13.

But the volumes being pumped were well below the full capacity of the pipelines, despite the insistence of European Commission president Jose Manuel Barroso that Europe needed the gas urgently. In a phone conversation with Putin, Barroso expressed his "disappointment with both the level of gas flowing to Europe" and the monitors' lack of access to pumping stations, world news agencies reported.