Adds detail from statement, complaint and effort to reach company in paragraphs 2-6

Jan 7 (Reuters) - The top U.S. watchdog agency for consumer finance on Tuesday sued credit rating giant Experian EXPN.L, saying the company failed American consumers who challenge the accuracy of consumer credit files, court records show.

Through a California subsidiary, the Ireland-based global data broker maintains crucial files on most American families but allegedly mishandles their complaints, damaging household finances in the process, the agency said in a statement.

Experian conducts "sham investigations" into consumer disputes and allows deleted false information to be reinserted into credit files, according to the CFPB.

Representatives for Experian did not immediately respond to a request for comment.

"Credit reporting errors can have serious consequences for a family's finances and it is critical that credit reporting giants follow the law," CFPB Director Rohit Chopra said in a statement.

The complaint seeks a court order barring Experian from further misconduct and requiring the company to pay redress to harmed consumers, to forfeit any resulting ill-gotten gains and to pay a fine.

(Reporting by Douglas Gillison; Editing by Chizu Nomiyama)

((douglas.gillison@thomsonreuters.com;))