MOSCOW (Reuters) - Russian natural gas exporter Gazprom said on Thursday that Ukraine's outstanding debt for gas supplies stood at $5.3 billion as of Aug. 1 and called on Kiev to ensure that gas continues to transit without disruption to Europe.

"Gazprom counts on Naftogaz of Ukraine to stick to its obligations on redemptions of arrears for the supplied gas and provision of smooth gas transit via Ukraine's territory," Gazprom spokesman Sergei Kupriyanov said.

Russia cut off gas supplies to Ukraine on June 16 in a dispute over unpaid bills. However, Russian gas shipments to Europe via Ukraine have flowed without interruptions since.

It is the third pricing dispute in a decade between the two sides and past standoffs have led to disruptions in supply to Europe.

About half of the gas Gazprom shipped to Europe last year went via Ukraine.

Ukraine wants to pay $268.50 per 1,000 cubic meters of gas - a price it was offered at the end of last year when pro-Moscow Ukrainian President Viktor Yanukovich was still in power. It has said it is ready to compromise.

Moscow has sought to keep the price at a 2009 level of $485 per 1,000 cubic meters, but has offered to waive an export duty, bringing prices down to $385, broadly in line with what Russia charges other European states.

A series of talks between Moscow and Kiev, brokered by the European Commission, have failed to find a compromise.

Russian President Vladimir Putin and Ukrainian counterpart Petro Poroshenko are due to attend crisis talks in Minsk on Aug. 26 in an attempt to resolve a confrontation over Ukraine which has plunged relations between the two countries to an all-time low.

Kupriyanov also said Gazprom had paid an additional payment of $10.54 million to Ukraine's state energy firm Naftogaz in July for gas transit.

Naftogaz said it will return the $10 million saying it was "paid in error", news agency Interfax Ukraine reported on Thursday.

(Reporting by Vladimir Soldatkin; editing by Jason Neely)