The Financial Industry Regulatory Authority will appeal a ruling that allowed Charles Schwab Corp to require customers to waive their right to participate in class-action suits, a spokeswoman said on Tuesday.

"We are in the process of filing an appeal," a FINRA spokeswoman told Reuters in an emailed statement. The decision comes after a hearing panel decision last Thursday that upheld Schwab's late 2011 move to require clients to waive their class-action rights. Schwab's action violates FINRA's rules, but the rules themselves violate the National Arbitration Act, the panel found.

A Schwab spokeswoman did not immediately return a call requesting comment.

FINRA, Wall Street's self-regulator, had 45 days to appeal to its National Adjudicatory Council, an appellate body for FINRA disciplinary decisions.

Class-action suits are the most common way for investors with small cases to try to recoup losses stemming from wrongdoing by Wall Street brokerages, say lawyers. Brokerage agreements usually require investors to resolve legal disputes in FINRA's securities arbitration forum - an option that investors with small cases often find too costly to pursue, they say.

FINRA prevailed in one part of the case: the panel ruled that Schwab could not bar group arbitration claims. It fined Schwab $500,000 for including language in its customer agreement that imposed such a restriction. The sanction will be stayed while the appeal is pending, the FINRA spokeswoman said.

(Reporting by Suzanne Barlyn and Jed Horowitz)