An aide to Italy's deputy prime minister Matteo Salvini, at the center of accusations the ruling League party sought millions of euros via a secret Russian oil deal, flew back-and-forth to Moscow last year, news website BuzzFeed said on Thursday.

Flight records show Salvini's former spokesman Gianluca Savoini went to Moscow on three separate occasions last year in the run-up to an October meeting where the proposed covert oil deal was discussed, BuzzFeed reported.

In the weeks after, he made a further three, unexplained trips to Russia, the report added, citing a joint investigation with two other websites Bellingcat and The Insider.