BRUSSELS, April 14 (Reuters) - Payment for Russian gas in roubles by European Union buyers would break the EU's sanctions regime against Moscow, an internal European Commission note said.

The note, making clear it is technical, preliminary, and based on an unofficial translation of the Russian Presidential Decree of March 31, said the law added several new layers of obligations on EU gas buyers, taking the effective completion of the purchase out of their hands.

"This mechanism would lead to a breach of the existing EU restrictive measures adopted in respect of Russia, its government, the Central Bank of Russia, and their proxies; as well as the general wide prohibition to circumvent and of the EU restrictive measures," the internal note said. (Reporting by Jan Strupczewski; editing by Jason Neely)