Rupert Murdoch’s REA Group has made a fourth attempt to buy Rightmove, increasing its offer to £6.2bn as it steps up its pursuit of the UK’s largest online property portal. The Australian property group, which is controlled by News Corp, raised its cash and shares offer from the £6.1bn offered earlier this week and called on Rightmove’s board to “engage now” after it refused repeatedly to meet the suitor. Rightmove has rejected three previous non-binding cash and shares approaches from REA this month, calling them “unattractive” and saying the offers “fundamentally undervalue” the company. In its latest offer, REA sweetened its cash and shares proposal with terms valuing each Rightmove share at 781p, and the entire company at about £6.2bn. Its initial proposed bid of 705p in early September had valued Rightmove at £5.6bn, before it made subsequent bids worth £5.9bn and £6.1bn. REA’s latest approach means that, for each share, Rightmove investors would receive 346p in cash and 0.0417 new REA shares and a special dividend of 6p in cash in lieu of any final dividend. In a statement, REA expressed “disappointment and surprise” at the repeated rejections by Rightmove and appealed directly to the UK company’s shareholders to persuade them to back the deal before the formal deadline of 30 September. REA said there had been no “substantive engagement” from Rightmove’s executives beyond “cursory procedural telephone calls” with Rightmove’s chair, Andrew Fisher. REA has until 30 September to make a firm offer or walk away. The bidder has pressed for an extension to the deadline, and said extra time should be granted to permit further engagement. The company urged investors to “use what little time remains ahead [of the Monday deadline] to make their views known to the board of directors of Rightmove”. In response to the latest offer, Rightmove said: “The board will consider the latest proposal together with its financial advisers and, in the meantime, shareholders are urged to take no action.” In 2001, Rupert Murdoch’s son Lachlan took control of REA, buying a 44% stake in the struggling Australian property company for A$2m (£1.3m). Since the Murdochs sold some of their media crown jewels and Rupert retired from leadership of the rest last year, the property company has taken on greater importance for News Corp. The investment is seen as one of Lachlan’s key contributions to the family’s wealth. Rupert is taking legal action to try to hand control of News Corp to Lachlan, who is thought to share his rightwing political views. Analysts have said REA’s pursuit of Rightmove, which controls more than 80% of the UK online property market, is opportunistic and undervalues the business, as the UK property market is rebounding. More than 1m properties are advertised on Rightmove each month. It raises cash by charging estate agents subscription fees to list properties, as well as selling other services. Rightmove and Zoopla, the second-biggest company in the sector, are facing stiffer competition after the US property company CoStar bought OnTheMarket last October. REA has said that if it acquired Rightmove it would give the company a secondary listing on the London Stock Exchange to open it up to a wider pool of investors. REA owns a number of property websites in Australia including realestate.com.au, property.com.au and the data company PropTrack, as well as brands in India and the US. It previously tried to expand into the UK but sold that operation to Zoopla in 2009. Owen Wilson, the chief executive of REA, said: “We continue to see the potential for us to strengthen Rightmove and accelerate its growth. This is a compelling opportunity to create a true global technology leader on the London market via a secondary listing, operating in two of the most attractive markets in the world.” Shares in Rightmove fell after the latest bid was announced on Friday morning, but rallied after Rightmove’s response, up 5p at 670p.