London, UK - Despite the steady decline of News Corp-owned MySpace, owner Rupert Murdoch has ruled out selling it - or buying Twitter.

He said Twitter had not yet come up with a way to make sustainable profits, and would therefore be a difficult investment to justify.

Twitter is widely regarded as being ripe for a takeover - and News Corp had been widely tipped as a possible buyer. But, speaking at Allen & Co's Sun Valley conference, Murdoch said, "Be careful of investing here."

Asked about selling MySpace, he said, "Hell no."

News Corp bought MySpace in 2005 for $580 million. But over the years, it has lost out to Facebook and also Twitter. MySpace recently laid off about 700 employees - a third of its staff.

Other possible purchasers tipped to buy Twitter have included Apple and Google.