"I don't think there is a graver crime than supplying arms to a conflict zone," Putin told his Ukrainian counterpart, Yulia Tymoshenko, during their meeting at the Russian premier's residence near Moscow.
He also said that he regretted "that Ukraine thought it acceptable to supply weapons to the conflict zone."
Putin also said Moscow had evidence proving that Ukrainian military experts were present in the conflict zone during the five-day war that began when Georgian forces attacked breakaway South Ossetia.
Russia earlier accused Ukraine of supplying Georgia with some of the heavy weaponry, including tanks and multiple-launch rocket systems, used in its attack on the rebel republic. Kiev has denied the allegations.