The deadline which Microsoft gave Yahoo to respond to its takeover offer passed at the weekend with the internet giant still refusing to budge.

At a quarterly earnings conference call last week, Microsoft's chief financial officer Chris Liddell warned Yahoo that Microsoft could pull its offer to buy the internet giant if Yahoo continues to hold out for a better deal.

Liddell also expressed frustration at Yahoo's "unrealistic expectations" of a higher sale price.

Microsoft must now choose whether to walk away from the deal or launch a hostile takeover by going directly to Yahoo's board members.

"As outlined in our recent letter to the Yahoo board, unless we made progress with Yahoo towards an agreement by this weekend, we will reconsider our alternatives, and provide updates as appropriate next week," said Liddell. "We have yet to see tangible evidence that our bid substantially undervalues [Yahoo]; in fact, we see the opposite."