One in three Americans and Brits is making unauthorized copies of DVDs, according to research sponsored by a maker of digital rights management systems.

Those numbers represent an increase over last year, when the same study showed one in four.

The second Consumer Home Piracy Market Research, conducted by Futuresource Consulting online last May, involved 3,613 consumers in the U.S. and 1,718 in Blighty.

Results, released Tuesday, showed that men 18-24 continue to do the most copying and that the U.K. is experiencing a significant increase in copying TV shows on DVD. Last year, 42% of U.K. consumers surveyed said they were copying TV shows. This year, 61% said so.

Both Americans and Brits showed a preference for copying newly released movies over catalog or library films. In the U.K. during the past six months, consumers copied an average of almost 13 new releases vs. nine catalog/library; in the U.S., consumers copied 7.4 new vs. six catalog/library.

In both countries the most popular source for copying DVDs was rented or borrowed discs.

Asked whether they would have purchased the films had they not been able to copy them, 63% of respondents in the U.K. and 77% in the U.S. said they would have purchased all, some or at least a few of the titles, "clearly indicating the scale of the lost revenues to the homevideo industry from home copying," a summary of the study said.

Study was funded by Macrovision, which develops and markets DRM systems.