(Reuters) - Australian property listing firm REA Group said on Monday it had sweetened the takeover offer for Rightmove to 6.1 billion pounds ($8.12 billion), after Britain's largest real estate portal rejected an earlier offer.

The latest offer implies a value of 770 pence per Rightmove share. Rightmove is yet to respond to this offer.

Rightmove rejected a 749 pence-per-share offer from REA earlier this month, saying it undervalued the company, REA said.

REA, which is majority-owned by Rupert Murdoch's News Corp, said it had initially offered 705 pence per share, or 5.6 billion pounds, for Rightmove.

($1 = 0.7510 pounds) (This story has been corrected to say that Rightmove rejected an earlier takeover offer and REA has since sweetened the offer to $8.1 bln)