Apple Inc. (Nasdaq: AAPL) is preparing a new lineup of thinner MacBook laptops running on more powerful chips made by Intel Corp., people with knowledge of the plans said.

The MacBook Pro machines, to be unveiled at Apple’s annual developers conference starting June 11, also will feature high-definition screens like those on the iPhone and iPad, as well as flash memory to cut startup times and extend battery life, said the people, who asked not to be identified because the plans haven’t been made public.

Apple’s Mac sales are growing faster than the personal- computer market, benefiting from the popularity of its mobile devices. Since 2007, when the iPhone was introduced, Apple’s Mac sales have more than doubled, reaching $21.8 billion last year. As Apple’s share has grown, competitors such as Hewlett-Packard Co., Dell Inc. and Samsung Electronics Co. have followed suit in making thinner, aluminum laptops that start up more quickly.

Apple’s new laptops will run on Intel’s new processors, code-named Ivy Bridge, and will have a slimmed-down body design from the current 0.95-inch thickness, the people said.

Bill Evans, a spokesman for Cupertino, California-based Apple, declined to comment, while Chuck Mulloy, a spokesman for Intel, referred questions to Apple.

Apple shares fell 1.5 percent yesterday to $558.22 at the close in New York. The stock has risen 38 percent this year.

Mountain Lion

At the developer conference, Apple also may announce the debut date of its latest Mac operating system, called Mountain Lion, one person said. The new software, which Apple previewed in February, more closely aligns Mac computers with its mobile devices — the operating system includes many elements of the iOS mobile software that runs the iPhone and iPad. One feature lets users send a text message to an iPhone from a Mac.

Mountain Lion also expands Apple’s iCloud digital-storage service to let Mac users access and share saved documents across the Internet. It also allows users to create and access reminders and notes, and receive notifications, on all their Apple devices. Another new iCloud feature will make it easier to share photographs, the Wall Street Journal reported yesterday.

The emphasis on the Mac at next month’s conference suggests that Apple will concentrate on the iPhone later in the year. Analysts, including Gene Munster of Piper Jaffray Cos., have predicted Apple will release its next smartphone model by October. The iPhone is Apple’s top-selling product, accounting for 58 percent of its revenue in the most recent quarter.

New Mobile Software

Apple is expected to preview some of the new mobile software features that will be part of that release at the developer conference in San Francisco.

While Mac computers account for just 13 percent of Apple’s sales and are no longer the main sales engine for the company, the machines are steadily gaining market share. Apple controlled 11.6 percent of the PC market in the U.S in the fourth quarter of last year, compared to 6.1 percent in the same period of 2007, according to Gartner Inc.

Apple last redesigned the body of the MacBook Pro in 2008. The devices have more memory and stronger graphical and computing capabilities than MacBook Air laptops. The MacBook Pro now costs $1,200 to $2,500, depending on the size and components.

The new models come as Apple looks beyond Intel for chips to power its iPhone and iPad. While Intel provides the semiconductors for Apple’s new laptops, the chipmaker is facing questions from investors about why it hasn’t made better inroads into the market for components that power phones and laptops. Instead of using the Santa Clara, California-based company for chips inside its mobile devices, Apple uses competing components based on the designs from ARM Holdings Plc.

Intel’s Goals

At an investor meeting last week, Intel Chief Executive Officer Paul Otellini was asked whether the company was at risk of losing the Mac business altogether if Apple moves its computers to an ARM design. He said Intel’s plan is to improve the performance of its designs to the point where Apple will use its products more widely.

Intel, the world’s largest chipmaker, also is helping boost Apple’s competitors in the PC market, who are seeking to respond to the popularity of Apple’s iPads and laptops by introducing their own new products. Intel has been promoting a new type of thinner laptop, called an Ultrabook, that uses its components. Ultrabooks are less than an inch thick, have days of battery life, start up in seconds and sell for less than $1,000. The features are similar to those of Apple’s MacBook Air.

Intel also has been working closely with Microsoft Corp. on the release of its Windows 8 operating system, which was designed to work on both PCs and mobile devices. The Ivy Bridge processor design is made with an updated manufacturing process, resulting in more powerful chips that use less battery life.

The technology website reported earlier yesterday that Apple is working on a thinner version of the MacBook Pro with a sharper screen.