Russia's state-run monopoly Gazprom announced it will resume shipping natural gas Tuesday to Europe, where tens of thousands of homes and buildings have been left without heat in freezing weather. Gas supplies will be restarted at 2 a.m. "if there are no obstacles," Gazprom deputy chairman Alexander Medvedev said in Brussels. The shift came after Ukraine signed off on an EU-brokered deal that sent teams of EU, Russian and Ukrainian monitors in to track the movement of Russian gas through Ukraine's vast pipeline system. Gazprom had shut off deliveries last Wednesday, accusing Ukraine of siphoning off gas intended for Europe, a charge that Ukraine denies. "As soon as [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," Prime Minister Vladimir Putin said at a cabinet meeting Monday. Russia supplies about one-quarter of the European Union's natural gas, 80 percent of it shipped through Ukraine, and the disruption has come as the continent is gripped by freezing temperatures. The gas cutoff has affected more than 15 countries, with Bosnia, Bulgaria, the Czech Republic, Hungary, Serbia and Slovakia among the worst hit. Sales of electric heaters have soared and thousands of businesses in eastern Europe have been forced to cut production or even shut down. Relief will not come immediately, however. It will take 24 to 30 hours for gas to reach European customers once Russia resumes pumping, EU Energy Commissioner Andris Piebalgs said. Russia was still not sending natural gas to Ukraine for domestic consumption. The two neighbors remained deadlocked over the price Ukraine should pay for gas in 2009 and the amount Russia should pay for transporting gas through Ukraine's pipelines. Russia stopped supplying gas to Ukraine on January 1 over the price dispute. 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. Gazprom would not say when its observers would be in place. "The EU, Russia and Ukraine will each name 25 monitoring experts," said Deputy Prime Minister Igor Sechin. "This will be sufficient to monitor the supply of gas at all monitoring points." Ukraine first signed the agreement early Sunday, but Russia declared it invalid after Ukraine attached additional conditions, including being able to use Russian gas to pump supplies across its vast territory. Gazprom says Ukraine must pay for that so-called technical gas, but Kiev insists it won't pay until the two countries strike their own gas deal and Russia restores gas deliveries to Ukraine. Ukrainian government officials clarified the deal Monday and said the declaration was not legally binding. "We will continue to use [technical] gas from the Russian Federation," Prime Minister Yulia Tymoshenko told reporters. "We will be able to pay for it when contracts are signed and we receive payment for transit." Gazprom has lost about $800 million in revenue because of the disruption of supplies, Putin told German ARD television. The anger toward Russia for shutting off supplies was particularly acute in eastern Europe, where many residents spent money they really couldn't afford on electric heating and temperatures plunged to -14 C (6.8 F) in places like Sarajevo, the Bosnian capital. "We switched our heating from gas to electricity," said Snjezana Kordic, a 51-year-old Sarajevo resident. "We will never again depend on the mood of the Russians."