MILAN, May 17 (Reuters) - Italian energy group Eni has started proceedings to open two accounts, one in euros and the other in roubles, to pay for Russian gas as it strives to maintain supplies without breaching sanctions.

The Italian energy group, one of Europe's biggest importers of Russian gas, said on Tuesday the move was a precautionary one and followed Gazprom's unilateral request to amend existing contracts under a new gas payment scheme.

"The company is going to temporarily open the two accounts without prejudice to its contractual rights, which still envisage payment in euros," Eni said in a statement.

State-controlled Eni said its decision had been taken in concert with the Italian government and in compliance with the sanctions framework.

Eni faces a deadline to pay Russia's state-owned Gazprom around May 20, after Moscow at the end of March demanded foreign buyers start to pay for gas in roubles or risk losing supply.

Uniper, Germany's largest importer of Russian gas, said on Tuesday it was transferring euros to an account at Gazprombank to comply with Moscow's demands, but made no mention of a separate rouble account.

Like peer RWE, Uniper faces a payment deadline at the end of May but has not specified a date.

ARBITRATION PROCESS

Countries and companies have for weeks been seeking clarity from the European Commission on how they can proceed with payments without breaching sanctions put in place after Russia's invasion of Ukraine.

Eni said, as requested by the European Commission, it had clarified with Gazprom from the beginning that it considered its obligations satisfied upon the transfer of euros.

Eni also said without further clarification from Gazprom it planned to start an international arbitration based on Swedish law, in accordance with current contracts, to resolve the uncertainty over the changes to payments.

In updated guidance on Friday, the Commission confirmed its previous advice that companies can still pay for Russian gas, so long as they do so in the currency agreed in their existing contracts and declare the transaction completed when that currency is paid.

EU sanctions do not prevent companies from opening an account at a designated bank, it added.

But a European Commission spokesperson said on Tuesday that opening an account in roubles at Gazprombank would breach the EU's sanctions regime.

In its statement, Eni said what it called "a clearing point agent operating at the Moscow Stock Exchange" would carry out the conversion into roubles within 48 hours without any involvement of the Central Bank of Russia. (Reporting by Stephen Jewkes; Additional reporting by Christoph Steitz; Editing by Keith Weir and Ed Osmond)