Microsoft has launched a test version of a Web-based MSN Messenger that allows people to connect to the instant messaging (IM) service without having to install any software.

The beta version comes a week after Microsoft accidentally gave a sneak preview on a test website. It swiftly removed the pages once discovered. The test itself is aimed at people in the US, UK, France, Germany and Japan. Plans are to expand the service later this year.

A Web-based IM client is useful in situations where installing the full client is not possible such as a public computer in a library, school or conference, or when using a locked-down corporate system.

Web-based instant messaging is not new. AOL has long offered AIM Express, Yahoo has a Web client for its Yahoo Messenger, and several third-party Web sites offer Web-based access to various instant messaging services, including MSN Messenger.

The beta version of MSN Web Messenger requires Internet Explorer 5.0, Netscape 7.0, Mozilla 1.6 or newer versions of any of these Web browsers. Users also must disable pop-up blocking and have a Microsoft Passport account, according to the test website.

MSN Web Messenger supports basic text messaging only, and does not support Web cams, audio conversations or online gaming, for example.