The decree, passed on Thursday, forces non-European Union parties to notify Rome of any takeover intentions or plans to acquire stakes in key financial infrastructure such as the bourse, the sources said.

The decree gives Rome the right to veto any stake building by non-EU players in such assets if it deems such a move a threat to national interests.

Italy's stock market, which includes a key trading platform for the country's bonds, is owned by the London Stock Exchange.

Earlier this month the Hong Kong bourse made an unsolicited takeover bid on the LSE which was rebuffed by the UK group.

(Reporting by Giuseppe Fonte, writing by Stephen Jewkes)