CUPERTINO, Calif. — Apple Inc. is tweaking the iPhone to work better with business e-mail, an expected move that is meant to address a key weakness in the popular consumer device.

The company said Thursday that the next software update for iPhones will enable them to work with Microsoft Corp.'s Exchange software, which is widely used by businesses to handle and secure e-mail.

Apple did not say when the update will be available.

The move puts Apple in more direct competition with Research in Motion Ltd.'s BlackBerry and Palm Inc.' Treo smartphones, which are popular among business customers. Many businesses have shied away from the iPhone because it doesn't work well with their e-mail systems.