A spokesman for America Online, Jim Whitney said Microsoft had contacted it on February 15 with a demand that it turn over documents Microsoft has been seeking to defend itself in the government anti-trust case being lodged against it.

A Microsoft spokesman said it had subpoenaed documents from the three companies to determine the effect of the agreements on competition, which is an issue in its trial.

Last November, America Online agreed to buy Netscape Communications for $4.2 billion in a three-way deal, in which Sun will resell Netscape's enterprise software and provide servers that manage networks to America Online.

Sun spokeswoman Lisa Poulson said Sun received a subpoena last week regarding its role in the AOL-Netscape merger.

Previously, Sun had voluntarily given the US department of justice copies of its six contracts with AOL so that the DOJ could share the documents with Microsoft. The subpoena followed, Poulson said.

``From our perspective, we delivered the relevant contracts without a subpoena, and we're willing to and have been working to deliver whatever other information is appropriate to Microsoft in a timely manner,'' Poulson said in a statement.

Sun and AOL said they have been working with Microsoft on meeting the Redmond, Washington-based company's requests, while also seeking to protect their ability to withhold competitive information that might be used against them.

The companies said they expect the issues raised by the subpoenas to be resolved by the end of this week.

Poulson said the subpoena Sun received asks for documents concerning the effect of Sun's deal and its related agreements on Microsoft operating systems, middleware, Web browsing software and any other software development platforms.

It also asks for documents related to the creation and distribution of Web browsing software, the number of subscribers to online services and estimates of traffic to the companies' Web sites and any documents mentioning the deal's possible affect on the US versus Microsoft lawsuit.

The request for information extends to documents tied to communications among AOL, International Business Machines Corp and its Lotus unit, Novell Inc and Oracle Corp, who collectively amount to most of Microsoft's major rivals.

It also requests documents tied to AOL's decision to continue to use Microsoft's Internet Explorer as the primary browser in its AOL service and any information related to the possibility of using Netscape or Sun Web browsing software in any future AOL service software.

This information was to be returned to Microsoft by February 22.

The Sun spokeswoman said Sun had delivered a good portion of the materials, and was negotiating with Microsoft's attorneys at the law firm of Sullivan and Cromwell on what else might be appropriate to search for and deliver.