WASHINGTON -- Consumer groups and the nation's publishers are going another round over the economics of college textbooks.

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In a new report titled "Ripoff 101," state Public Interest Research Groups said textbook prices have risen at nearly four times the rate of inflation in the last 10 years.

The groups accused publishers of issuing expensive new editions that are often unnecessary. According to the report, new editions of textbooks cost, on average, 45 percent more than used copies of the previous edition.

The group also said publishers sometimes pack new textbooks with costly bells and whistles like CD-ROMs. The report also said American students pay more for the same textbook -- sometimes twice as much -- than students in other countries.

A related study offered similar findings last year.

On its Web site, the Association of American Publishers called the new report "flawed" and claims tuition and fees have gone up at a much faster rate than textbooks.

“I am concerned that PIRG is failing to focus on the real needs of today’s college students, ignoring new professional research, using selective numbers and making apples and oranges comparisons to draw conclusions that misrepresent the facts,” said Patricia Schroeder, president and chief executive officer of the Association of American Publishers.

According to PIRG, the average college student spends nearly $900 each year on textbooks.