Gazprom, Russia's state-run energy provider, has said it will restart gas deliveries to Europe through Ukraine after differences over an EU-brokered monitoring agreement were finally resolved.
The gas is expected to start flowing on Tuesday to the 15 European countries that have been suffering in bitter winter conditions without heating since supplies were cut off last Wednesday.
The deal signed in Brussels on Monday set out the procedures for international observers to deploy to strategic points along the gas export route to check no gas is being stolen - a condition set by Russia for resuming supplies.
Russia turned off the gas after a row over payments and claims by Moscow that Kiev had siphoned off supplies bound for Europe.
"As soon as they [the monitors] are at the control points, and we are sure that they can control the transit of our gas, Gazprom will pump gas to Ukraine's gas transit system to be shipped to European customers,'' Vladimir Putin, Russia's prime minister, said at a cabinet meeting on Monday.
Teams of EU monitors and officials from Naftogaz, Ukraine's state-run energy company, were already at six major gas transit stations on Ukraine's border with European countries and at three units on the Russian-Ukrainian border, according to Naftogaz.
"It is unbearable that Russia and Ukraine carry out their conflict in the middle of a grim cold winter on Europe's back"
Germany's economics secretary
Gazprom did not say when its observers would be in place.
"The EU, Russia and Ukraine will each name 25 monitoring experts," Igor Sechin, Russia's deputy prime minister, said. "This will be sufficient to monitor the supply of gas at all monitoring points."
Gazprom and Ukraine have said it will be at least 36 hours after supplies are restarted before gas reaches the freezing countries in Europe.
Eastern Europe has been badly hit by the gas shutdown, with several countries forced to look to alternative means of power or to use their reserves.
Russia supplies about one-quarter of the European Union's natural gas and 80 per cent of it shipped through Ukraine.
"It is unbearable that Russia and Ukraine carry out their conflict in the middle of a grim cold winter on Europe's back," Peter Hintze, Germany's economics secretary, said in Brussels.
An attempt to resolve the dispute over the weekend faltered after Ukraine added handwritten amendments to a deal stating that Kiev had not siphoned off European-bound gas and had no outstanding debts to Gazprom.
Russia subsequently said the changes had nullified the agreement.
Kiev dropped the additions under pressure from the European Union.
Ukraine itself will remain cut off from Russian gas because the two sides are still deadlocked over the price Kiev will pay for gas in 2009. Ukraine says it has enough gas stockpiled to last until spring.
"Ukraine held out and can hold out much more," Andriy Goncharuk, an aide to Ukraine's president, told a news conference in Kiev.