MILAN, April 15 (Reuters) - Consob gave a green light on Thursday to pan-European stock market operator Euronext's takeover of Borsa Italiana, a source close to the Italian market regulator said. Last year Euronext triumphed over rival SIX and Deutsche Boerse to agree to buy Milan's Borsa Italiana from the London Stock Exchange for 4.3 billion euros ($5.1 billion).

Ahead of the deal's expected closing in the first half of 2021, Euronext had detailed its plan for Borsa to Consob.

Confirming reports in the Italian press, the source said Consob had expressed a positive opinion on the deal in a letter to Euronext.

To secure Rome's backing in the race for Borsa, Euronext had teamed up with state investor Cassa Depositi e Prestiti (CDP) and Italy's biggest bank Intesa SanPaolo.

However, the change in ownership of an infrastructure deemed of strategic national relevance is stirring concerns among Italian politicians.

Consob, which will retain its oversight of the Italian market, also had concerns about retaining full access to bourse data which it needs to exercise its functions, a person familiar with the matter said on Wednesday

Italy's Treasury and the prime minister's office on Thursday sought to ease political and regulatory concerns by saying that the Milan bourse was set to play a key role within Euronext.

"The supervision of Borsa Italiana will remain unchanged, allowing Consob and the Bank of Italy to continue to directly supervise Borsa Italiana," they said in a note published on the economy ministry's website.

"Italy will be a major operational base for the Euronext Group, with a strategic role in terms of technology, business and support functions", they said.

Euronext's finance operations will be based in Milan, while the European market operator is considering also moving its data centre to Italy from the UK where it is currently based. (Reporting by Andrea Mandalà and Elisa Anzolin in Milan, Giuseppe Fonte in Rome, editing by Kirsten Donovan)