Brussels/Prague - Ukraine and Russia remained at loggerheads Thursday over the deployment of international experts to monitor gas flows through Ukraine, European Union officials said.

While both sides have agreed that international monitors could play a role in solving the standoff which has crippled gas supplies to Europe, officials said that no final agreement on a mission had been reached during talks in Brussels.

"We need to get an agreement on the monitors, and the devil is in the detail," Czech deputy premier Alexandr Vondra, whose country holds the EU's rotating presidency, said at an informal meeting with EU foreign ministers in Prague.

The head of Russian gas monopolist Gazprom, Alexei Miller, said that he would continue talks with his Ukrainian counterpart, Oleh Dubyna, while sharing a flight from Brussels to Moscow.

Miller and Dubyna both flew to Brussels on Thursday to lobby for EU support in their ongoing row, which has seen Gazprom cut off all gas supplies to Ukraine and via the country to Europe.

The EU reacted with outrage to the cutoff, with the bloc's foreign ministers issuing a joint statement demanding the instant restoration of gas supplies and the deployment of EU experts to Ukraine to make sure any gas sent to Europe arrives at its destination.

"Both sides have to date shown insufficient determination to solve the problem, which damages their credibility. The EU, however, expects that the current negotiations will bring a quick solution," the statement said.

Both Miller and Dubyna told the European Parliament and EU officials that they were committed to finding a quick solution to the row, raising hopes of a possible breakthrough.

And EU officials said that the bloc was ready to send a team of experts into Ukraine to make sure that any gas sent through the country to Europe reached its destination.

Russia claims that it cut off gas supplies to Ukraine because Ukraine was stealing gas meant for European consumers - a claim Kiev hotly denies.

"Monitors are ready to be there tomorrow if necessary," Vondra said.

But the talks in Brussels bogged down in the question of where, when and how the experts could be deployed.

"News that all has been settled is not yet true ... Tomorrow is an important date," Vondra said.

Russia supplies some 25 per cent of all the gas burnt in the EU, and 80 per cent of that passes through Ukrainian pipelines.

The dispute has left many EU countries facing gas shortages just as the continent is suffering from one of its coldest winters in decades. (dpa)