Social networking site Facebook launched a next-generation online messaging service on Monday that included email addresses in a move seen as a shot across the bow of Google, Yahoo! and Microsoft.

Facebook founder Mark Zuckerberg unveiled what he called a ‘convergent' modern messaging system that “handles messages seamlessly across all the ways you want to communicate.'' The messaging service blends online chat, text messages and other real-time conversation tools with traditional email, which Mr. Zuckerberg said had lost favour for being too slow for young Internet users.

“It is true that people will be able to have email addresses, but this is not email,” Mr. Zuckerberg said at an event in downtown San Francisco.” It handles email.

Mr. Zuckerberg dismissed reports referring to the messaging system as a ‘Gmail killer' aimed at the heart of free Web-based email services from Google and similar services from Yahoo! and Microsoft. The Facebook messaging service was intended to turn online exchanges into ongoing conversations as opposed to intermittent back-and-forth email missives, according to Facebook director of engineering Andrew Bosworth.