Ruport Murdoch has said that News Corp will not make a direct bid to take over Yahoo, but has refused to rule out co-operation with Microsoft on the matter.

Speaking before the US Atlantic Council, the media figurehead said that Microsoft's position is simply too strong to be competed against. "I certainly can't afford to bid against Microsoft," he said.

But when asked about his interest in the possible future of Yahoo, Murdoch added that it would "depend on the deal."

And the News Corp managing director hinted that a Microsoft-Yahoo merger might be the only viable opposition to Google's dominance in web-based marketing.

"Is Google really going to get control of the advertising world, and should Microsoft be supported in their attempt to try and stop that?" he said.

Yahoo now has until Saturday to give a final response to Microsoft's $44.6bn (£22.5bn) takeover offer. The software giant has said that it may attempt to incite shareholder revolt if the search firm opts to decline.

Both companies are due to publish their financial results this week.