Gas giant Gazprom said on Wednesday it was halting all natural gas supplies to Ukraine after pricing talks broke down in the latest row between Russia and its ex-Soviet neighbor.

"Ukraine did not pay for July gas supplies," Gazprom chief Alexei Miller said in a statement.

"Gazprom has halted gas supplies to Ukraine from 10 am (0700 GMT) July 1," he said.

He stressed that no more gas would be sent to Ukraine without prepayment no matter what the future price will be, adding that the gas pricing formula for Ukraine would not be changed until late 2019.

The Kremlin declined to comment.

The announcement came after Ukraine declared Tuesday it was suspending all purchases of natural gas from Russia after EU-mediated negotiations in Vienna aimed at keeping supplies running broke down.

Ukraine's state energy company Naftogaz indicated that gas supplies to Europe would not be affected, saying it would continue transporting Russian gas supplies westward to its other European clients.

On Wednesday Ukraine's energy minister Volodymyr Demchyshyn said Kiev was ready to continue talks.

A senior European official said that gas supplies to Ukraine and the EU would not be endangered.

"Both gas deliveries to Ukraine and transit to the EU are not endangered," said ­Maros Sefcovic, the European Commission's vice-president for energy union.

Russia supplies around a third of Europe's gas, half of it flowing via Ukraine.

Moscow dramatically hiked the price it charges Ukraine following the ouster of president Viktor Yanukovych in 2014.

Kiev is now increasingly ­relying on supplies from ­central European countries and energy-­rich Norway.

On Wednesday, Ukrainian gas pipeline operator Ukrtransgaz spokesman Maksim Belyavsky confirmed transit gas supplies had not been affected.

Belyavsky said Ukrtransgaz had on Wednesday received only a request from domestic clients for gas that enters Ukraine through western neighbor Slovakia.

According to ­Ukrtransgaz, over the past six months Ukraine has imported 6.3 ­billion cubic meters of gas from Europe and 3.7 billion cubic meters of gas from Russia.

Russia had offered to keep the price it charges Ukraine through the end of September at $247 per thousand cubic ­meters of gas.

That figure represents a $40 discount from the price Russia had the right to set under the terms of a prior agreement.

But Russian Energy Minister Alexander Novak said Ukraine wanted a discount of at least 30 percent.

End-of-year haggling over energy prices has been a f­amiliar problem between ­Russia and Ukraine, with ­Moscow having cut natural gas to Ukraine and disrupted transit supplies to Europe in the past.