Pan-European stock market operator Euronext announced Monday it has submitted an offer to buy Milan's Borsa Italiana from the London Stock Exchange Group in partnership with Italy's CDP Equity and Intesa Sanpaolo.

Euronext, which is competing against Germany's Deutsche Boerse and Switzerland's SIX Group for the Italian stock exchange operator, said there is no certainty that the "non-binding" bid will lead to a transaction.

The potential for a bidding war over Milan's stock exchange was opened after its current owner, the London Stock Exchange Group (LSEG), said in July it was prepared to sell the subsidiary to win approval by the EU Commission of its planned purchase of US financial data provider Refinitiv.

According to sources familiar with the negotiations, Swiss market operator SIX's offer would give Borsa Italiana ample autonomy and a considerable amount of investment, including in technology.

No financial details on the offers have been released, but, according to the Bloomberg news agency, Borsa Italiana could fetch between 3.5 and 4.0 billion euros.

Italian economic news agency Radiocor cited sources close to the matter as saying that SIX's offer was the highest.

SIX is a privately-held company and is not obliged to make its offer public.

SIX could also raise its bid without seeing its own share price tumble in exchange.

In addition to operating the Milan stock exchange, Borsa Italiana also has trading platforms for government bonds, a clearing house for trading operations plus a depository, which would make it a valuable addition to all three bidders.

Euronext said last week it teaming up with Italy's CDP Equity, part of a state-held banking group, to make its bid for Borsa Italiana.

On Monday it added it would be joined by Intesa Sanpaolo, Italy's largest bank by capitalisation.

"The proposed combination of Borsa Italiana and Euronext would create a leading player in continental European capital markets, where Italy would be the largest revenue contributor to the enlarged Euronext group," it said in a statement indicating the importance of the Italian operator.

Euronext, which runs a handful of European stock exchanges including the one in Paris, has been on a shopping spree recently, buying the Danish Central Securities Depository, VP Securities, last month to expand its Nordic footprint.

It also acquired the Scandinavian electricity exchange Nord Pool in January and the Oslo Stock Exchange in June 2019.

By contrast, it decided not to buy the Madrid stock exchange, which was eventually snapped up by SIX.

Rome has said all offers will be examined closely by the government and the regulatory authorities.