By MIGUEL HELFT

Facebook has more than 500 million users around the world. And Americans spend more of their time online with Facebook than with any other Internet company, including Google and Yahoo.

Now the company wants people to weave their online lives even more tightly into Facebook.

On Monday, Facebook is expected to unveil a revamped set of communications services that will include an e-mail system in which users will have addresses with the facebook.com suffix, according to two people briefed on Facebook’s plans who asked to speak on condition of anonymity because they were not authorized to discuss them publicly.

Facebook has invited reporters to a press conference on Monday, but has refused to say what it plans to announcement. The company declined to comment on any unannounced communications services.

Facebook already offers an online chat service and a rudimentary system to exchange messages with other Facebook users. The new services, whose exact details could not be learned, will greatly expand Facebook’s communications offerings.

But one person with knowledge of Facebook’s plans said that the new communications services will not be meant to be used on their own, like other e-mail systems. Instead, they will be tightly coupled with Facebook’s other services.

“They are not trying to do a standalone rival to Gmail,” the person said. “The are building an integrated experience in everything they do.”

Still the new services could sharpen Facebook’s competition with Google and others.

“All of the e-mail vendors should be worried – Google, Yahoo, MSN,” said Jeremiah Owyang, an analyst with the Altimeter Group, who was not briefed on Facebook’s plans. “All of those platforms have been trying to add social networking features to their services.”

TechCrunch first reported on Friday that plans to unveil new communications services at the Monday press conference.

Facebook’s new communications services come on the heels of a series of new product announcements by the company in recent months. Facebook recently unveiled a service that allows users to announce their location and that borrows from services like Foursquare and Gowalla; a Groups feature, that allows its users to share items with select groups of friends; and a service allowing merchants to offer users coupons and special offers on their mobile phones.

Like these features, the new communications services are “an opportunity for Facebook to spend more time with consumers,” Mr. Owyang said. “The more they own of our digital day, the more money they will make.”