The delegation of top officials from the Czech Republic, which currently holds the EU's rotating presidency, and the European Commission, the EU executive, is reportedly set to hold talks with Ukrainian political leaders and representatives of the gas industry.

The delegation is also due to meet officials from Russian gas monopoly Gazprom on Monday or Tuesday, depending on their respective schedules. Gazprom has already sent a delegation of top officials to Europe to present its side of the dispute.

The mission is headed by Czech Industry Minister Martin Riman. He is accompanied by his country's special envoy for energy, Vaclav Bartuska, and officials from the office of EU Energy Commissioner Andris Piebalgs.

The EU mission is intended to "keep up intense contacts" with the two sides, whose row over contracts and allegedly unpaid bills led Gazprom to shut off gas deliveries to Ukraine on Thursday, Jan. 1, a Czech spokesman said.

Brussels seeks solutions

Meanwhile, EU diplomats later Monday are to hold an emergency meeting in Brussels to exchange information over the gas crisis. EU energy experts are set to meet in Brussels on Friday.

Since the row began, Russia and Ukraine have issued conflicting accounts on who is to blame for the shut-off and the extent to which supplies to Europe would be affected.

Reports from EU member states in central and eastern Europe have also given contradictory versions of the current state of gas supplies, leaving EU authorities groping for accurate information.

The fact-finding mission had been planned for later this week, but was brought forward to avoid a clash with the Orthodox Christmas on Wednesday, Jan. 7, a Czech spokesman said.

Supplies affected in the Balkans

Gazprom said Ukrainian authorities had shut down the Orlovka Compressor Station which supplies gas to the Balkans.

Bulgaria's state gas distributor Bulgargaz said Russian gas transit volumes via Bulgaria to Turkey and Macedonia were lower as a result of the standoff.

Supplies to Romania were 30 percent lower, while the Czech Republic saw a 5 percent drop Sunday, though the government in Prague said gas levels had returned to normal Monday.

Croatia said natural gas deliveries from Russia had dropped 7.5 percent as a result of the dispute, but added that supplies to domestic customers would not be affected.

Greece, meanwhile, has seen a drop of nearly one-third in its gas supplies.

Both sides threaten court action

With no immediate end in sight, both Moscow and Kyiv have said they would bring cases against each other at an arbitration court in Stockholm that handles commercial disputes.

Gazprom Chief Executive Alexei Miller will meet Russian Prime Minister Vladimir Putin on Monday for talks on the standoff, a Russian government spokeswoman said

The EU is heavily reliant on Russian gas passing through Ukrainian pipelines for its energy needs. Gas pipes laid across Ukraine carry about a fifth of the EU's gas requirements.

In early 2006, a similar Russo-Ukrainian dispute caused gas shortfalls across much of Europe.