Rightmove said in a statement that the cash and shares proposal, worth £5.6 billion (US$7.3 billion), “was wholly opportunistic and fundamentally undervalued” the company.

REA made public its interest in Rightmove on September 2, noting “clear similarities” between the pair “in terms of their leading market positions in the core residential business”.

Sector-watchers said REA could be attracted by the prospect of more interest-rate cuts in Britain which would lower mortgage costs for buyers, as well as by the new government’s plans for mass housebuilding.

“REA Group’s bid for Rightmove was highly opportunistic and so it’s little surprise that it’s been rejected for fundamentally undervaluing the company and its future prospects,” said Susannah Streeter, head of money and markets at Hargreaves Lansdown.

“REA Group runs property websites and indices across Australia, Asia and North America, so getting a dominant foothold in the UK would be very attractive,” she added.

In a separate statement Wednesday, REA said its offer was worth 705 pence per Rightmove share.

The British group traded up 0.6 percent at 675 pence in reaction to the latest updates, giving it a market value of about £5.3 billion.

REA added Wednesday that should it succeed in buying Rightmove, it would apply for a secondary stock market listing in London, in addition to its current trading on the Australian Securities Exchange.

“This would provide the opportunity for a wider pool of investors to gain exposure to a global and diversified digital property company on the London Stock Exchange,” it said.

REA has until September 30 to announce a firm intention to make an offer for Rightmove.