The Yuliya Tymoshenko Bloc party said in a statement that the government of Prime Minister Yuriy Yekhanurov should resign if it fails to secure an agreement with Russia's state-controlled Gazprom company by the end of the year.
On 13 December, Gazprom said it could stop supplying gas to Ukraine if no agreement is reached by the end of the year.
President Viktor Yushchenko fired Tymoshenko, a former Orange Revolution ally, in September complaining of her economic policies. Since then, she has emerged as a strong political competitor ahead of parliamentary elections next March.
(Interfax/"Ukrayinska pravda")