YouTube is doubling the size of its online video store in an expansion that will make more movies available for Internet streaming at the same time they're released on DVD.

The move announced Monday escalates the competition in a still-developing market that already includes some of technology's most powerful companies.

YouTube is hoping to lure business away from Apple Inc.'s iTunes store and Amazon.com Inc.'s website, which also rent online video on a pay-per-view business. All three services are trying to undercut Netflix Inc., whose subscription video service has added more than 13 million customers during the past two years to underscore the growing popularity of watching movies over high-speed Internet connections instead of on DVDs.

Under new licensing deals reached with several major studios, YouTube says it will be adding about 3,000 titles to its rental library, which is only available in the U.S.

That will leave YouTube with about 6,000 rental selections 16 months after it opened the store. Until now, few of the movies in YouTube's rental store were available at the same time as the DVD releases, putting it at a competitive disadvantage.

Most of YouTube's movies rent for $3 or $4 per viewing, comparable with competing services. For most titles, renters will have up to 30 days to begin watching a video, but must complete the viewing within 24 hours after starting.

Unlike the pay-per-view plans, Netflix's streaming library of more than 20,000 titles offers an unlimited amount of viewing for as little as $8 per month. Few of Netflix's streaming options are available at the same time as the latest DVD releases.

YouTube's rental store marked the latest step in its evolution from a website for quirky homemade videos to an outlet for more traditional fare from television, movie and music producers. Winning over Hollywood has taken some time because YouTube emerged as a haven for pirated video clips almost as soon as the service launched in 2005. Google imposed more anti-piracy tools after buying YouTube for $1.76 billion in 2006.

Despite the improved controls, some studios are still carrying a grudge. Viacom Inc. is trying to revive a lawsuit seeking more than $1 billion in damages for YouTube's alleged piracy. A federal judge in New York last year ruled that YouTube hadn't broken U.S. laws governing digital piracy, but Viacom is appealing the decision.

Viacom-owned Paramount Pictures so far hasn't agreed to rent its movies through YouTube's store. Other holdouts include News Corp.'s 20th Century Fox and Walt Disney Studios, which rents its movies through Apple's iTunes store. Apple CEO Steve Jobs is Walt Disney Co.'s largest shareholder and a member of its board.

The studios that have agreed to rent their latest releases through YouTube include NBC Universal, Sony Pictures and Warner Brothers.