San Francisco, Nov 13 (DPA) Facebook is set to announce a new email feature Monday that could challenge Gmail, Yahoo mail and Hotmail as the most popular online email services, according to news reports.

The service by the popular social networking company will for the first time allow the site's 500 million members to use "@facebook.com" addresses and will also be integrated with Microsoft's recently introduced Office online services.

The tech news blog TechCrunch, which first reported the development, said the Facebook service would be a full-featured email client.

"Facebook is completely rewriting their messaging product and is preparing to launch a fully featured webmail product in its place, according to a source with knowledge of the product," TechCrunch wrote.

The development comes amid growing rivalry between Facebook and Google, which this week raised salaries across the board to preempt defections to the social network site.

Google also recently cut off Facebook's access to its own email product to prevent Facebook from importing Gmail address books until Facebook allows Google to access data on its site.