Ukraine and Gazprom yet to reach agreement
This raises new questions over how Ukraine will repay its US$ 1.5 billion debt to the firm.
Following talks with Gazprom CEO Aleksey Miller, Timoshenko told journalists a lot of problems had cropped up and she was determined not to leave until all the issues were solved.
Gazprom's spokesman confirmed that the talks would continue.
This comes despite a meeting last week between the Russian and Ukrainian Presidents, when they agreed the debt would be repaid, and that the present intermediary company RusUkrEnergo would stay in place.