Microsoft is looking to acquire search company Yahoo according to US press reports.

Microsoft and Yahoo have held informal talks in the past, with the US software giant making an offer for Yahoo that was turned down, according to Friday's New York post, citing unnamed sources. The fresh talks suggest a renewed urgency on Microsoft's part to make a deal, the paper said. The Wall Street Journal also reported that the companies were in "early-stage discussions" .

Financial analysts have valued Yahoo at approximately US$50 billion, the Post reported. Goldman Sachs is working with Microsoft, it said.

Google announced early last month that it would buy DoubleClick in cash, bolstering the search company's status as an online advertising powerhouse. Microsoft had also been interested in DoubleClick and was understood to have lost out in a bidding war with Google, analysts said at the time.

Microsoft and Yahoo have both been struggling to rein in Google's lead in the search and online advertising markets. Losing DoubleClick and a few other deals to Google, including an advertising tie-up with AOL two years ago, gave Microsoft renewed interest in a merger with Yahoo, the Post reported. "They're getting tired of being left at the altar," a banking source told the Post.

Acquiring Yahoo would expand Microsoft's presence on the web and could make it easier for the software giant to attract new advertising customers. And Yahoo could benefit from Microsoft's technical expertise, the Journal said.

Despite heavy investments in its own search engine and search ad network, Microsoft has not matched the levels of online advertising revenue that Google and Yahoo have achieved. Traffic to Microsoft's web sites is strong - it consistently ranks first in website visitors worldwide - but the company has not made as much money from that traffic as it would like.

Microsoft and others, including two civil rights groups, have asked regulators to examine Google's planned DoubleClick acquisition, saying it would be bad for competition in the online advertising market.

Microsoft and Yahoo could not immediately be reached for comment.