Microsoft has signed an agreement with Yahoo allowing it to have access to the web giant’s books and operations as it explores options to complete a deal – potentially an acquisition – with the company, reports Reuters.

Yahoo has been undergoing a strategic review to revamp its business and deal with stagnant revenue growth since firing Carol Bartz as CEO in September, apparently due to boardroom concern that her turnaround plan for the firm was not producing results.

Since then Yahoo has reportedly been touting itself to be either partially of completely acquired, attracting interest from private equity firms such as KKR and TPG Capital, which have signed similar confidentiality agreements. Reuters sources say some private equity firms have been put off signing this kind of agreement with Yahoo due to restrictions preventing the formation of consortiums.

In October, Microsoft was rumoured to have renewed its interest in buying Yahoo more than three years after its proposed US$44.6 billion takeover of the company fell through. Google was also reported to be considering providing finance to another company or group of companies to fund the acquisition of Yahoo.

Yahoo has so far failed to pursue a coherent mobile strategy although in recent weeks it has introduced a number of mobile apps, including the long-awaited Livestand media aggregation app – first unveiled at Mobile World Congress in February – as well as the IntoNow TV app and Yahoo Mail app for iPad and Yahoo Weather for Android. The company also launched an Android app store in Japan, although this currently only provides reviews and links through to Android Market.