“Spider-Man 3,” “Ratatouille,” “Superbad,” “No Country for Old Men” and many more big-screen hits will be available online, as Netflix Inc. announced on Tuesday that it has reached a deal with Liberty Media’s Starz Entertainment and will add approximately 2,500 movies, TV shows and concerts to its Web streaming service.

The terms of the deal, however, were not disclosed.

The agreement represents a very important move for Netflix, as its “Watch Instantly” streaming service, which makes available for viewing a library of more than 12,000 titles, mainly includes older releases. In spite of the fact that the number of online watchable videos is outshined by the approximately 100,000 titles the world’s largest movie rental service has available on DVDs, Netflix explained that it intends to increase both numbers and thus reduce the difference in the long run.

The added Starz films will be incorporated in the Netflix “Watch Instantly” service at no extra charge to subscribers with unlimited subscription plans.

Some 10 days ago, Netflix signed a deal with Disney and obtained the rights to stream Disney Channel hits such as “Hannah Montana,” “The Suite Life of Zack & Cody” and “Wizards of Waverly Place.”

In addition to this, the company also reached a deal with CBS Corp. to stream several television series, including “CSI,” “NCIS” and “Numbers.”

About 1,000 of the Starz titles will be made available immediately on the Netflix Web site, while the other videos will be added during the next few weeks, the companies explained.