DUBAI, June 20 (Reuters) - United Arab Emirates renewable energy company Masdar said on Thursday it has reached an agreement to buy an initial 67% stake in Greece's Terna Energy and intends to make a mandatory offer to buy the rest.

Masdar has signed a definitive agreement with Greek conglomerate GEK Terna and other shareholders to buy the 67% stake in Terna Energy at 20 euros ($21.45) per share.

The acquisition price gives the Greek renewables company an equity valuation of 2.4 billion euros and an enterprise value of 3.2 billion euros, the two companies said.

GEK Terna owned 37.93% of Terna Energy as of June 4, according to LSEG data.

The transaction is subject to regulatory approvals and other conditions. Once completed, "Masdar will launch an all-cash mandatory tender offer to acquire all the remaining shares of TERNA ENERGY with the intention of reaching 100%," the statement said.

Masdar is expanding in several parts of Europe, as well is in Asia, the United States and elsewhere, as it seeks to grow its capacity to 100 gigawatts of renewable energy by 2030.

Masdar is owned by state-controlled energy and utilities firm TAQA, Abu Dhabi sovereign wealth fund Mubadala and Abu Dhabi National Oil Company, which hold stakes of 43%, 33% and 24%, respectively.

"As one of Europe's biggest renewable energy transactions in 2024, this investment reflects the UAE's clear commitment to Greece and Europe's clean energy development," said Sultan Al Jaber, Masdar's chairman and president of the COP28 climate summit hosted by the UAE last year.

Rothschild & Co was financial adviser to Masdar and Simmons & Simmons, Bernitsas Law and Latham & Watkins were legal advisers for the deal and financing.

Reed Smith and Potamitis Vekris were legal advisers to GEK Terna Group and Morgan Stanley was financial adviser to Terna Energy. ($1 = 0.9323 euros) (Reporting by Yousef Saba. Editing by Jane Merriman)