ROME (Reuters) -Generali will buy out the Spanish unit of U.S. insurer Liberty Mutual for 2.3 billion euros ($2.51 billion), in a move aimed at strengthening its property and casualty segment, Italy's top insurer said on Thursday.

"Generali is acquiring a profitable insurance business in three growing European markets with very attractive characteristics, that will create significant long-term value for all stakeholders," Chief Executive Philippe Donnet said in a statement.

Generali said it expects the acquisition to bring a reduction of 9.7 percentage points on the group's regulatory solvency ratio.

The all-cash deal would allow the Italian group to become one of the main players in the Spanish insurance market, as well as enter Ireland and Northern Ireland, Generali said.

Citigroup and Credit Suisse acted as financial advisers for the transaction, it added.

($1 = 0.9179 euro)

(Reporting by Federica Urso in Rome and Shivani Tanna in Bengaluru; editing by Jonathan Oatis)