A growing number of Indian tribes are getting into the payday loan business, saying they just want to raise revenue for their reservations while helping cash-strapped consumers nationwide.

But federal officials suspect that, at least in some cases, tribes are being paid to offer their sovereign immunity to non-Indian payday lenders that are trying to dodge state regulations.

So far, the tribes have prevailed over California and other states that have tried to assert authority over tribal lending operations. But they may now face a crackdown by the federal Consumer Financial Protection Bureau.

"The states have historically been the ones that have regulated and overseen the payday-loan industry," said Tom Feltner, director of financial services for the Consumer Federation of America.

"They're the ones that have implemented rules for interest rates or even whether a payday loan can be issued," he said. "The vast majority of these tribal lenders are not complying with state laws."