KYIV, Nov 22 (Reuters) - Ukraine denied an assertion by Russian state gas company Gazprom on Tuesday that Ukraine had withheld gas meant for Moldova, and accused Russia of using gas as a political tool to limit supplies to Europe.

Accusing Ukraine of keeping volumes of gas that were destined for Moldova, Gazprom said it could start reducing gas supplies to Moldova via Ukraine from Nov. 28.

"Russia is not the first to use gas as a tool of political pressure. This is a gross manipulation of facts in order to justify the decision to further limit the volume of gas supplies to European countries," the Ukrainian gas transmission system operator (GTSOU) said in a statement.

It said all natural gas "accepted from the Russian Federation at the entry point 'Sudzha' for further transportation to Moldovan consumers were transferred to the exit points ... to Moldova in the full amount."

Moldova's president warned her country on Monday to brace for a harsh winter as it faces an energy crisis, with Russia's war in Ukraine threatening energy supplies and pushing up prices.

GTSOU said Gazprom wanted to deprive Moldova, a tiny former Soviet republic bordering Ukraine, of the opportunity to use the Ukrainian gas transmission system and Ukrainian underground gas storage facilities, increasing its dependence on Russian gas at the start of the heating season.

Ukrainian state energy company Naftogaz added on Twitter: "Gazprom accused Ukraine of stealing gas once again. In short: this is not true." (Reporting by Pavel Polityuk, Editing by Timothy Heritage)