Kyiv's decision to let lapse its contract with Gazprom to supply Russian gas to Europe will seriously harm European consumers, the Kremlin said on Wednesday.

Ukrainian President Volodymyr Zelensky on Tuesday said his country would not extend the transit agreement via Ukraine beyond December 31.

"It's over," he said.

Despite the ongoing conflict, Russia delivered more than 14 billion cubic metres of gas to Europe via Ukraine in 2023, although this was less than the 40 billion cubic metres provided for in the contract.

EU members Austria, Hungary and Slovakia still receive Russian gas in this way.

The three countries continue to rely on Russian gas despite an EU pledge to free itself of Russian gas by 2027 following Moscow's full-scale offensive into Ukraine launched in February 2022.

"Such a decision by Ukraine will seriously harm the interests of European consumers who still want to buy Russian gas," Kremlin spokesman Dmitry Peskov said.

"They will simply have to pay much more, which will make their industry less competitive," he added.

Ukrainian companies signed the five-year contract with Gazprom at the end of 2019.

Last month, Zelensky had indicated that Ukraine was in discussions with Azerbaijan, a major producer of natural gas, to replace Russian gas transiting Ukraine.

However, Ukraine does not share a border with Azerbaijan, which would imply that Azerbaijani gas would still have to be transported by pipeline via Russia.

Azerbaijani President Ilham Aliyev said in late July that the EU and Kyiv had approached him to help discussions with Moscow to reach an agreement.

Since August 6, Ukraine has staged an unprecedented cross-border counter-offensive into Russia's Kursk region, seizing dozens of settlements, including the town of Sudzha.

The town of about 5,000 people is home to the Sudzha metering station, the last major transit point for Russian pipeline gas still heading to Europe via Ukraine.