KIEV, Dec. 26 - Ukraine's jailed ex-prime minister Yulia Tymoshenko has urged President Viktor Yanukovych not to "surrender" the country's natural gas pipeline system to Russia and has blasted him for "throwing the country back decades" by failing to achieve a deal the European Union a week ago on closer ties between Ukraine and the EU.

"I hope you don't have the brainwave to give up the gas transmission system. It is our last strategic resource. In fact, you are only welcomed at Gorki [the Russian president's countryside residence outside Moscow] because this system still belongs to Ukraine. When that is lost, you won't have a single argument left either for yourself or for the country," Tymoshenko said in her "Letter to the Dictator" quoted on the website of her Batkivschyna (Fatherland) Party on Monday.