Russia's Gazprom has suspended gas deliveries to Italy's Eni, blaming a transport problem in Austria, the Italian energy giant said on Saturday.
"Gazprom told us that it was not able to confirm the delivery of the volumes demanded for today, citing the impossibility of gas transport through Austria," Eni said in a statement.
As a result, "Russian gas flows to Eni via the Tarvisio entry point will be naught," it said.
Most of Russian gas delivered to Italy passes via Ukraine through the Trans Austria Gas Pipeline (TAG), to Tarvisio in northern Italy on the border with Austria.
Gazprom later in the day said in a statement that the transportation of Russian gas through Austria had been suspended "due to the refusal of the Austrian operator to confirm the transport nominations."
"The reason is related to the regulatory changes that took place in Austria at the end of September," it added.
"Gazprom is working on solving the problem together with Italian buyers."
In Austria, regulatory authority E-Control said the new rules, which entered into force on Saturday, had been "known to all market actors for months."
It said it expected "all to conform and take the necessary measures to fulfil their obligations."
The problems were linked to "contractual details" linked to the transit of gas towards Italy, it said on Twitter.
Before the war in Ukraine, Italy imported 95 percent of the gas it consumes - about 45% of which came from Russia.
Outgoing Prime Minister Mario Draghi has signed new deals with other gas producers to reduce Italy's reliance on Russia, lowered to 25% as of June, while accelerating a shift towards renewable energies.