Warner Bros. has stopped selling its new releases to Blockbuster in an attempt to force the chain to accept a 28-day rental window. Warners wants Blockbuster to wait that long before renting out DVDs or Blu-rays, the way Netflix and Redbox do.

The once giant rental chain is resisting, however, and bought copies of Horrible Bosses and The Green Lantern from outside sources, rather than the studio, for rental.

Those two movies are the first that Warner released on Ultra Violet-enabled discs, which let people store the movies in an internet cloud and watch them on a variety of devices.

Warners Bros. confirmed the standoff, reported in the Financial Times on Wednesday, but declined further comment. Blockbuster also declined to comment.

The report also suggested that the latest standoff may be a precursor to renewed windows battles between the studio and Netflix and Redbox in coming months.

With DVD and Blu-ray sales slumping badly and rentals on the rise, studios are scrambling to boost purchases of discs and digital copies.

Blockbuster, bought out of bankruptcy by Dish Network earlier this year, recently launched a subscription service designed to compete with Netflix.

Warner Bros. home entertainment president Kevin Tsujihara told the FT that Blockbuster felt it was important to continue to offer day and date rental, so rather than work with us, they went around us.

Tsujihara told the FT that the studio would like to make that waiting period longer -- and that deals with Netflix and Redbox both end at the end of the year.

The next agreement likely will include longer windows.