UPDATE 1-Lithium explorer Liontown rejects $3.7 billion buyout offer from Albemarle

(Adds details on offer)

March 28 (Reuters) - Liontown Resources said on Tuesday it had rejected a non-binding indicative proposal from top lithium producer Albemarle Corp, which valued the Australia-based battery metals explorer at A$5.50 billion ($3.66 billion).

Albemarle's A$2.50 per share offer represents a 63.9% premium to ASX-listed Liontown's last close.

"(The Liontown board) unanimously determined that (the proposal) substantially undervalues Liontown, and therefore is not in the best interests of shareholders," the company said.

Liontown currently controls two major lithium deposits in Western Australia, including its flagship Kathleen Valley project. The project is one of the world's largest and highest-grade hard rock lithium deposits, according to Liontown's website.

The company also said it recently became aware that RT Lithium Ltd, a subsidiary of Albemarle, has been building a stake in Liontown through on-market purchases. RT Lithium now holds a near 2.2% stake in Liontown.

Charlotte, North Carolina-based Albemarle is the world's largest lithium producer with major facilities in Chile, China and Australia.

($1 = 1.5033 Australian dollars) (Reporting by Harish Sridharan in Bengaluru; Editing by Sriraj Kalluvila)