* Shares soar up to nearly 19%

* Estia shareholders to get A$3.20/share under new offer

* Estia board intends to recommend offer

June 7 (Reuters) - Australia's Estia Health on Wednesday said it intended to back Bain Capital's sweetened takeover offer that valued the aged-care provider at A$826.8 million ($552.05 million), sending its shares about 19% higher to a near five-year peak.

Under the revised proposal, Bain Capital would offer A$3.20 in cash for every Estia share, which represents a 25.5% premium to the stock's last closing price, and up from a previous offer of A$3.00, Estia Health said in a statement.

"Following careful consideration, the board has determined that it is in the interests of shareholders to progress with the revised proposal and allow Bain Capital to undertake further due diligence to enable it to provide a binding proposal."

The firm had earlier provided limited access to its books in April to the U.S. investment company in hopes of a sweetened bid.

Additionally, Estia's board is also permitted to pay a fully-franked dividend of A$0.12 per share, allowing eligible shareholders to receive up to about 5.1 AU cents per share in franking credits. ($1 = 1.4977 Australian dollars) (Reporting by Sameer Manekar and Archishma Iyer in Bengaluru; Editing by Rashmi Aich)