Russian Prime Minister Vladimir Putin lashed out at Ukraine Thursday for delivering weapons to Georgia, overshadowing talks with his Ukrainian counterpart that ended in a draft agreement on gas pricing.
Putin sharply criticised the ex-Soviet republic over what he said was weapons used by Georgia to fight Russia during a brief conflict in August.
"A more serious crime than arms deliveries in a conflict zone cannot be imagined," Putin said.
"Several years ago, we could not have imagined Russians and Ukrainians making war against each other, but that has happened and it's a crime."
The comments came amid tense relations between Moscow and Kiev over the conflict in Georgia, but the two prime ministers were able to reach a draft agreement that seeks to resolve the delicate issue of gas prices.
Gas prices have been a sore point between the countries, and much of Europe also has a stake in whether the issue is put to rest.
Russia has in the past cut supplies to both Ukraine, which is heavily dependent on Russian energy, and Western Europe over gas prices.
"The parties have confirmed their good will in moving gradually, in three years, to market prices," Ukrainian Prime Minister Yulia Tymoshenko said after the meeting outside Moscow.
"We don't need shock therapy in terms of prices," she added at a joint press conference with Putin.
Ukraine eventually paying market prices for gas would mean a major increase on what it pays now.
Tymoshenko said last week she expected Ukraine to sign a deal with Russia by the end of October on the delivery of gas from 2009 for a period of up to four years.
Soaring prices were seen as potentially complicating talks, however, after Russian gas monopoly Gazprom announced prices for European clients had hit an all-time high of 500 dollars per 1,000 cubic metres.
Ukraine currently pays 179.5 dollars per 1,000 cubic metres and Russia has long been pushing Kiev to pay more, resulting in a series of price disputes intertwined with the two countries' rocky ties.
In 2006 one such dispute led Moscow to cut off gas deliveries to Ukraine and, by extension, to Western Europe, which gets much of its gas from Russia and Central Asia via pipelines running through Ukraine.
Tymoshenko later met with Russian President Dmitry Medvedev, his press service reported according to Interfax news agency.
Domestically, Ukraine is in the grips of its own political turmoil.
Tymoshenko and her arch-rival Ukrainian President Viktor Yushchenko have been feuding bitterly in a political uproar that began when the president pulled his party out of their ruling pro-West coalition after a dispute over how to respond to the war in Georgia.
Yushchenko's office accused the prime minister of "treason" for not being tough enough on Russia.
Media reports had said Moscow was pressuring Tymoshenko to ally with pro-Russian forces in Kiev, but she denied any such links between the "price of gas and the composition of the future coalition" in Ukraine.
Putin on Thursday alluded to the situation and the effect it could have on any deal between Moscow and Kiev.
"In concluding accords today we might wonder what will become of them tomorrow," he said.
The pro-Kremlin daily Izvestia on Thursday accused Yushchenko of selling Georgia air-defence systems and rocket launchers used in the attack on South Ossetia.
On Wednesday, Tymoshenko denounced arms trafficking in Ukraine and blamed Yushchenko and his allies for not stopping it, Interfax news agency reported.
The squabbling threatened Thursday's meeting with Putin when Yushchenko's plane made an emergency landing near Kiev, and Tymoshenko's team accused him of seizing her plane as she was about to leave for Moscow.
"The government delegation was deprived of its plane in a bid to thwart the negotiations" with Putin, a Tymoshenko spokesman was quoted as saying by Interfax. The prime minister arrived in Moscow aboard a chartered plane.
Ukraine's president and prime minister have had a love-hate relationship since 2004, when they joined forces in the so-called Orange Revolution to overturn the rigged election of a pro-Russian candidate as president.