The statement by Ukraine's space agency follows a report published by the International Institute for Strategic Studies, alleging that the rocket engines were procured from a plant in the former Soviet Union.
Ukraine's space agency said on Tuesday that an engine type reportedly used in North Korean missiles was made at a Ukrainian factory, but solely for use in space rockets supplied to Russia.
The development came after an expert report published on Monday said Pyongyang's recent rapid progress in developing a long-range missile appeared to have come after it refurbished rocket engines procured from a plant in the former Soviet Union.
The International Institute for Strategic Studies said these could have been bought from corrupt workers at arsenals in Russia or Ukraine and smuggled to North Korea by criminal networks at some point between the collapse of the Soviet Union in 1991 and Ukraine's current crisis.
"Such engines were made up to 2001 by Ukraine's Yuzhmash (plant),", Ukraine's acting space agency chief Yuriy Radchenko told journalists. He said the RD-250 engines were used in Cyclone-2 and Cyclone-3 space rockets supplied to Russia.
Both the engines and the space carrier rockets "were made at Yuzhmash in the interests of Russia," Radchenko said. In total, 233 such rockets were produced, used in space launches.
The space agency chief said that according to Ukrainian information, "Russia today has between 7 and 20" of the Cyclone rockets and could do whatever it wanted with the engines and blueprints.
"They have these engines, they have the documentation. They can supply these engines from the finished rockets to whoever they want."
Concerns over rocket fuel
The IISS report suggests Kim Jong-Un's regime, which successfully tested intercontinental ballistic missiles in July that are believed to have brought the US mainland within reach, has abandoned attempts to modify the Russian-built OKB-456 rocket engine and has now switched to the once Ukrainian-made RD-250.
During the Soviet era, the RD-250 was produced at the Yuzhmash plant in Dnipro, a city that is today in central Ukraine, around 150 kilometers (80 miles) from an active frontline held by Russian-backed separatists.
Ukraine did not act as a supplier of the engines to any other country, Radchenko said.
Radchenko also said that in his view, it was only possible to use these engines with technology for producing rocket fuel that only Russia and China have at their disposal.
"In order to use these engines and a missile properly, you need to have access to technology to produce rocket fuel. North Korea doesn't have such technology and basically only two countries have this: Russia and China."
Russian Deputy Prime Minister Dmitry Rogozin said it was not possible for North Korea to have copied such engines without help from Ukrainian specialists and smuggled engines or blueprints.
"In order to make a copy, you need to have either the original engine or detailed blueprints," he wrote on Facebook.
"And you can't manage without the Ukrainian specialists capable of and ready to set up production."