A Microsoft deadline for Internet service company Yahoo to accept its $ 44.6 billion (28.5 billion-euro) attainment offer expired at midnight on Saturday, setting the step for a hostile takeover bid by the software giant. The expiration of the Sunday 0700 GMT deadline, without comment from either side was likely to surface the way for a repulsive proxy clash, a battle by Microsoft for a vote by Yahoo shareholders to place pro-Microsoft officials on its board of directors.

In an open letter to the Yahoo board of directors on April 5, Microsoft chief executive Steve Ballmer gave the internet pioneer three weeks to accept the 31 dollars-a-share takeover offer or face a proxy fight. Ballmer also warned that any further delays could result in a less attractive offer for Yahoo. But Yahoo’s board of directors has said the offer “substantially undervalues” the California firm, insisting the company is worth at least 40 dollars a share.

Microsoft is keen to unite the two companies’ resources to take on Google, which dominates the rewarding Internet search advertising market which is expected to grow to 80 billion dollars annually worldwide in the next two years.