"We sincerely expect that all earlier reached agreements will be implemented and from our side we guarantee full implementation," Putin said after talks in Yalta with Ukrainian Prime Minister Yulia Tymoshenko.
"It would be very good to meet the New Year without any shocks," Putin said.
The Russian prime minister said Russia had agreed not to impose fines on Ukraine if it failed to use the volumes of gas it had agreed to. He added that Russian payments to Ukraine for gas transit would rise 60% in 2010 in line with earlier agreements.
His words seem likely to relieve the European Union, which has anxiously monitored the talks in Yalta, southern Ukraine, for indications of whether a new end-of-year gas conflict endangering supplies to EU consumers was on the cards.
Tymoshenko told Putin that Ukraine would scrupulously fulfil its obligations on the transit of Russian natural gas to Europe.
"We will very carefully and distinctly carry out our part in the transit of the gas," the prime minister of Ukraine is quoted as saying.
Before the talks, Putin had warned that Russia would cut gas deliveries again - or siphon off transit gas - if Ukraine stopped paying on time, under an agreement worked out last January.
The January agreement, which the Russian prime minister brokered with Tymoshenko, ended a conflict over gas pricing which led to Russian gas flows to Europe via Ukraine being halted for two weeks in mid-winter. Millions in southern Europe were left without heating.
Russian supplies across Ukraine provide Europe with a fifth of its gas and earlier this week an anxious EU agreed with Russia an 'early warning' mechanism to shield Europe from potential energy supply reductions in the event of further cuts.
But relations between Russia and the pro-Western leadership of the former Soviet republic have slid further in the run-up to a presidential election on 17 January. The gas deal has also become mired in infighting in Ukraine between Tymoshenko and President Viktor Yushchenko, her political rival.
Though Ukraine has so far settled all its bills on time, Tymoshenko has conceded that, given the dire state of the economy, meeting the monthly payments for gas is a struggle.
But she told Putin on Thursday: "Ukraine has paid and will pay on time."
Using warm words which contrasted with a frosty exchange earlier in the day between Moscow and Kiev, Tymoshenko said the agreement she had brokered with Putin in January had represented a "breakthrough" in their energy cooperation.
Moscow snub
The Kremlin earlier snubbed Yushchenko, who had called for a revision of the gas agreement. It accused Kiev of trying to blackmail Russia and Europe over energy supplies.
In an open letter to Russian President Dmitry Medvedev, published on his website, Yushchenko said: "Keeping the contracts unchanged [...] will create potential threats specifically to the reliability of supplies of gas to Ukraine and its transit to other European states."
He believes the price accepted for Russian gas was too high while transit fees coming to Ukraine were pitched too low.
Tymoshenko herself says the 10-year supply contract agreed with Russia does not have to be revised and provides for stable supplies of gas in 2010.
Kremlin aide Sergei Prikhodko, speaking to journalists in Moscow, poured scorn on Yushchenko's plea to Medvedev.
Ridiculing Yushchenko and Tymoshenko for constantly squabbling, he said: "We are categorically against energy security in Europe becoming dependent on the personal ambitions of Ukrainian politicians."
"The attempt to intimidate Russia and Europe with forecasts of a crisis in the transit of gas -- this already looks something like political blackmail," he said.
Prikhodko said gas relations between the two countries had a solid juridical base.
"Of course these are not set in stone and we are always open to negotiations with our Ukrainian partners," he said.
Medvedev last summer publicly wrote off relations with the pro-western Yushchenko, accusing him of pursuing anti-Russian policies.
(EurActiv with Reuters.)
