Yulia Tymoshenko thinks the gas deal was a bad one

Ukraine agreed to almost double what it pays for its neighbour's gas this year after a bitter price dispute which saw Russia cut off supplies for three days.

There is lingering dissatisfaction with the agreement on both sides, with Russia wanting to raise prices further.

Ms Tymoshenko said discussions should take place "in a friendly manner".

Priority issue

The pro-western politician, sacked as prime minister last year after falling out with President Yushchenko's aides, has persistently called for Ukraine to reduce its payments to Russia.

She is now set to return to power after the three parties which backed the 2004 "Orange Revolution" agreed to form a coalition government following months of negotiations.

I think all issues on gas supplies to Ukraine now require further deep revision and review Yulia Tymoshenko

She told reporters that reviewing the gas deal would be one of her priorities after returning to office.

"I think all issues on gas supplies to Ukraine now require further deep revision and review," Ms Tymoshenko said.

Ukraine, which imports most of its gas from Russia, is now paying $95 per 1,000 cubic metres for its gas - compared to $50 this time last year.

Russian gas monopoly Gazprom wanted more than $200 per 1,000 cubic metres, but eventually agreed to mix its gas with cheaper supplies from Turkmenistan. It now delivers the gas via a deal with an intermediary firm, RosUkrEnergo.

Turkmenistan, meanwhile, is now threatening to limit its deliveries to Gazprom unless it is paid more for its gas, a development which could threaten the Ukraine deal.

Russia has claimed that the terms of the agreement can be renegotiated this summer although Kiev has previously disputed this.