(Adds no comment from LSE)
By Giuseppe Fonte and Pamela Barbaglia
ROME/LONDON, June 10 (Reuters) - As the London Stock Exchange seeks approval for its $27 billion takeover of Refinitiv, uncertainty over the fate of its Italian exchange and bond-trading operations has caused rifts among politicians in Rome, two sources told Reuters.
The governing 5-Star Movement is seeking to lure Italy's biggest financial institutions, including Intesa Sanpaolo , to launch a bid for the Milan Bourse that would avert a possible break-up of the business triggered by the Refinitiv deal, the sources said, speaking on condition of anonymity.
But the plan has run into opposition from some coalition partners.
Economy Minister Roberto Gualtieri - a prominent member of the centre-left PD party - opposes an Italian bid for all or parts of Borsa Italiana, the sources said.
A senior official close to the Treasury told Reuters a takeover offer was "not something the Finance Ministry is currently studying".
The LSE, Borsa Italiana and the Treasury declined to comment.
The Five Star proposal was crafted with the help of Antonio Guglielmi, Mediobanca's executive vice chairman of corporate and investment banking. It aims to form a consortium that would back a possible bid by state lender Cassa Depositi e Prestiti (CDP) for Borsa Italiana or its bond-trading platform MTS, the sources said.
Intesa and investment firm Unipol have been identified as possible anchor investors for the bid, which would also involve a series of Italian financial institutions that manage pension schemes on behalf of industry corporations, the sources said.
The proposal values the Milan exchange at about 3 billion euros ($3.40 billion), the sources said.
Its main promoter is Cabinet Undersecretary Riccardo Fraccaro who is in charge of supervising and managing policy issues for Prime Minister Giuseppe Conte, they said.
Representatives for Mediobanca, Intesa and Unipol declined to comment.
The move comes as European Union antitrust regulators are probing the LSE deal for Refinitiv, raising the prospect that MTS could be hived off as part of any antitrust remedies to clear the deal.
A decision on whether to take the deal to a second phase of investigation is expected on June 22.
Rome sees MTS as an asset of strategic interest as it offers a platform to trade Italian sovereign bonds, the sources said.
But several other sources, who are familiar with LSE's strategy, said any divestment of MTS would hinge on the outcome of the European antitrust review.
One of the sources, who is close to the 5-Star camp, said that Economy Minister Gualtieri would favour a tie up between Borsa Italiana and French stock exchange Euronext.
Euronext's Chief Executive Stephane Boujnah approached the LSE to express interest in Borsa Italiana after LSE investors voted in favour of the Refinitiv deal in November, two sources close to the matter said.
But Boujnah's overture was rebuffed by LSE's boss David Schwimmer, they said.
Euronext declined to comment.
Five Star politicians worry Euronext may come back for all or parts of Borsa Italiana and want state lender CDP to take a stake in the Italian exchange to give it a say on strategic decisions, the sources said.
While 5-Star is not against a possible merger of Borsa Italiana with Euronext, it wants Italy to have the upper hand in any negotiation, they said.
Italy has extended its "golden power" legislation to block any move for the Milan Bourse.
$1 = 0.8814 euros Reporting by Giuseppe Fonte in Rome and Pamela Barbaglia in London; additional reporting by Huw Jones, Valentina Za and Andrea Mandala; Editing by Jon Boyle and Barbara Lewis