A Microsoft deadline for Internet service company Yahoo to accept its 44.6-billion-dollar (28.5-billion-euro) acquisition offer expired at midnight Saturday, setting the stage for a hostile takeover bid by the software giant.

Neither of the two sides made any comment as the Sunday 0700 GMT deadline came and went.

The deadlock was likely to pave the way for an ugly proxy battle — a fight 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.