(Adds Dorian's comment. Updates shares)
OSLO, May 29 (Reuters) - Norway's BW LPG, the world's largest liquid petroleum gas shipper, said on Tuesday it had offered to buy competitor Dorian LPG in a $1.1 billion all-stock deal in an effort to boost its earnings in a weak market.
Dorian shareholders will receive 2.05 BW LPG shares for each Dorian share, equal to $7.86 per share, a premium of 13 percent from Friday's closing price, and based on BW LPG's share price on May 28.
Shares of Dorian closed 5.2 percent higher at $7.32, its best day since December 2017.
In a separate statement, Dorian confirmed BW LPG's "unsolicited proposal", adding that its board was reviewing the offer.
New York-listed Dorian LPG's equity is valued at about $441 million and including debt the transaction is valued at $1.1 billion.
The deal is backed by shipping conglomerate BW Group, owned by the Hong Kong-based Sohmen-Pao family, which owns 14.2 percent of Dorian and about 45 percent of BW LPG.
Dorian LPG's fleet consists of 22 very large gas carriers (VLGC) and the combined company would own 73 vessels, of which 68 would be very large gas carriers, 2 VLGCs currently under order and 3 large gas carriers if the deal goes through.
BW LPG said it expected minimum annual savings of $15 million from the deal. (Reporting by Ole Petter Skonnord; Editing by Adrian Croft and Anil D'Silva)