Data breaches at US companies doubled last year and are cost substantially more than other internal IT gaffes, according to new research.

The incidence of malicious attacks rose from 12 percent in 2008 to 24 percent last year, according to the a survey to be released by the Ponemon Institute and sponsored by PGP Corp.

Every record compromised cost an average of $215, 40 percent higher than breaches of negligence and 30 percent higher than those arising from glitches or bugs.

The average organizational cost of a data breach increased nearly 2 percent to $6.75 million in 2009, while the average cost per compromised record per breach rose only $2 to $204.

The most expensive breach was nearly $31 million and the least expensive was $750,000.

Mistakes at 3rd-parties represented 42 percent of all cases reported, while and 36 percent of the cases involved lost or stolen laptops or other mobile devices.

For the study, 45 U.S. companies from 15 different industries were surveyed.