A new report by the National Consumer Law Center, a consumer advocacy organization based in Boston, has concluded that the three major credit-reporting agencies — Equifax, Experian and TransUnion — have not done enough to improve the process by which consumers may correct these errors.

An industry group representing the agencies disputes the findings.

The Law Center’s report, released in late January, was based on an aggregation of research conducted over the last decade by various consumer groups and included a recap of Congressional testimony offered by executives of credit-reporting agencies and consumer advocates in 2007. The report found, among other things, that the agencies handled disputes in a “perfunctory” or “formalistic” manner.

The report’s principal author, Chi Chi Wu, a staff lawyer with the Law Center, said in an interview that anecdotal evidence from consumer advocates suggested that the problems cited in the report had not abated. The dispute process, she said, remains unnecessarily complicated.

Under the Fair Credit Reporting Act, consumers are entitled to have mistakes corrected, but they are required to contact the credit-reporting agencies directly rather than the creditors. (Credit card companies are an exception; consumers may dispute errors directly to them and expect a reply.)

But Ms. Wu says that the credit bureaus generally fail to forward to the creditors any supporting documentation sent to them by the consumer, like canceled checks. Rather, the disputes are essentially boiled down to two-digit codes that represent a category of complaint, and then they are forwarded to creditors.

The creditors “might then simply look at their computer records, which put out the wrong information in the first place, and reject the dispute,” Ms. Wu said. “It’s not what most people think of as a real investigation.”

According to the Consumer Data Industry Association, a trade group that represents credit-reporting agencies, “up to 3 percent” of the reports contain errors. Other consumer groups, however, say the rate is much higher; some put it as high as 25 percent.

“But even at 3 percent, that’s still millions of people,” Ms. Wu said.

Stuart K. Pratt, the president of the Consumer Data Industry Association, said consumers were partly to blame for the lack of detail about their discrepancies. He acknowledged that the credit bureaus “do have the opportunity to add some granularity to the coded dispute that goes off to the lender.” But 55 to 60 percent of consumer disputes contained no supporting documentation, he said.

And most consumers who supply documentation, Mr. Pratt added, include only standardized forms offered on a credit bureau’s Web site, rather than extensive documentation of their own.

“Most consumers don’t want to work too hard to have it taken care of,” he said.

According to Rebecca Kuehn, an assistant director of the Federal Trade Commission’s division of privacy and identity protection, consumers may soon see improvement in the process by which they dispute credit-reporting errors.

The Obama administration is expected to announce new rules later this year that would allow consumers who find mistakes in their reports to contact the creditors directly. The creditors would be required to respond to the consumers. “That way,” Ms. Kuehn said, “we won’t be cutting out the most important line of information — from the consumer to the company that’s providing the information in the first place.”

Once this new regulation is announced, the companies covered by this rule will have six months to a year before they must comply, according to Ms. Kuehn.