Property listing website Rightmove has rejected a takeover approach from a rival Australian site backed by Rupert Murdoch.

The £5.6bn offer from REA Group, which is majority-owned by Mr Murdoch’s News Corporation, was described by Rightmove’s board as “wholly opportunistic”.

In a statement on Wednesday, they said REA Group had “fundamentally undervalued Rightmove and its future prospects”.

The rejection is another blow for the Murdoch business empire after the failure of Talk TV earlier this year.

REA said in response it plans to list on the London Stock Exchange to directly compete with Rightmove.

The offer valued Rightmove at over quarter of its share price on 30 August. It would have meant Rightmove shareholders owning around 18.6% of the new merged business.

REA said its plan is to create a property business with “strong margins and significant cash generation’ that holds the number one position in both the UK and Australia.”

It added that buying Rightmove would “enhance the UK property experience for buyers, sellers, and renters, positively contributing to the property market ecosystem.”

Following the rejection from Rightmove’s board, REA has until 5pm on 30 September to bid again or accept it was rejected.

The news comes as hedge fund Starboard Value confirmed it filed a shareholder resolution to reduce Mr Murdoch’s power at News Corp.

The hedge fund wants to abolish the structure which currently gives Mr Murdoch 40% of News Corp’s voting stock even though he only owns an equity stake of about 14%.

Mr Murdoch stepped down as Fox and News Corp chairman in favour of his son Lachlan in 2023.

Earlier this year, the company signed a multi-year deal with artificial intelligence firm OpenAI, which means content from the likes of the Wall Street Journal, the New York Post, and the Times will feed content to AI bots like ChatGPT.

Mr Murdoch first bought a stake in REA in 2001and now News Corp owns 61% of its shares.

The media tycoon’s net worth is estimated at just over $20bn (£15bn).