The European Union's brand new Czech presidency was forced to urge Moscow Friday evening to resume full gas deliveries after the bloc's fears of drop in vital gas supplies became a reality.

"The European Union calls for an urgent solution to the commercial dispute on gas supplies from the Russian Federation to Ukraine, and for an immediate resumption of full deliveries of gas to the EU member states," the EU presidency said in a statement.

"Energy relations between the EU and its neighbors should be based on reliability and predictability. Existing commitments to supply and transit have to be honored under all circumstances," it added.

Pipeline pressure is down in the main pipes leading from Ukraine into EU members Hungary, Poland and Slovakia, the Czech Republic's energy envoy, Vaclav Bartuska, told German new agency dpa.

"It is so far only a decrease in pressure. The volumes (being delivered) remain the same ... The Ukrainian side told us that volumes will be down tomorrow (Saturday)," Bartuska said.

Russia is the EU's largest single supplier of natural gas, and 80 percent of its deliveries pass through Ukrainian territory.

Extraordinary meeting called

The EU's Czech presidency has called an special meeting of envoys from the 27 member states for Monday to discuss the gas dispute between Russian and Ukraine, a spokesman said.

"We are convening an extraordinary meeting ... at deputy ambassadors' level on Monday where the Russia-Ukraine gas dispute will be the sole topic for discussion," a spokesman for the Czech presidency told the AFP news agency on Friday.

The goal of the meeting will be "to exchange information" and "to coordinate the EU's response to the matter," he told AFP, repeating that so far there were no signs that European gas supplies had been hit.

Repeat performance

Three years ago, Gazprom shut off gas supplies to Ukraine in a near-identical row over gas prices and allegedly unpaid bills, causing sudden shortages across much of Europe.

Unlike on that occasion, EU member states had widely anticipated the current shut-off, which comes in the context of increasingly tense relations both between Moscow and Kiev's pro-Western government and between Ukraine's president and prime minister.

EU governments were careful to make sure that their gas stocks were full ahead of winter, meaning that the current shut-off is unlikely to have a short-term impact on supplies, EU sources said.

Battling versions of events

In recent days, Russia and Ukraine have both conducted intense diplomatic campaigns to present the other side as the troublemaker in the dispute. The prime ministers of both countries called European Commission head Jose Manuel Barroso on New Year's Eve to present their respective versions of the row.

An EU expert group on gas supplies is set to meet with member states' representatives in Brussels on January 9. Gazprom is set to send an official to the meeting, while Ukraine is expected to send a delegation to Brussels in the coming days, officials said.

However, analysts say that both sides' reputations have already been tarnished in the row, with the EU increasingly keen to find gas supplies which come from countries other than Russia and pass through countries other than Ukraine.

EU reliance on Russian gas varies from zero in Britain and Ireland to 100 per cent in the Baltic states and Slovakia, according to the Paris-based International Energy Agency. Germany, the EU's largest economy, obtains some 40 percent of all the gas it uses from Russia.