New York Attorney General Eliot Spitzer sought dismissal of a case brought by a banking regulator, saying it attempts to strip states of their power to probe mortgage-lending practices at national banks.

The U.S. Office of the Comptroller of the Currency, which regulates national banks, sued Mr. Spitzer’s office for seeking mortgage data from nationally chartered institutions. The agency and several banks, including JPMorgan Chase & Company and HSBC Bank USA, said Mr. Spitzer exceeded his authority in requesting the information. A federal judge last month stopped the attorney general’s probe until the lawsuit is settled.

“The OCC does not have the authority to promulgate rules that strip states of their statutory and common law authority to investigate and bring judicial actions to enforce non-preempted state laws,” Mr. Spitzer wrote in a counterclaim filed late Friday in the U.S. District Court in Manhattan.

Mr. Spitzer’s office argued that the agency’s efforts to prevent him from obtaining lending data run contrary to laws giving state regulators enforcement authority to punish discriminatory lending. The attorney general and consumer groups accused federal regulators of turning a blind eye to unfair lending.

Mr. Spitzer asked the judge to declare that the National Bank Act doesn’t take away the states’ authority to enforce non-preempted state laws against national banks.

The OCC’s rulemaking is “arbitrary, capricious, an abuse of discretion, and otherwise not in accordance with law, as well as in excess of the OCC’s statutory jurisdiction, authority and limitations,” Mr. Spitzer wrote in the brief.

The comptroller’s lawsuit, he wrote, “is nothing more than a naked attempt to expand the OCC’s power.”

Mr. Spitzer in April launched an inquiry into the mortgage lending practices of at least three banks – JPMorgan, HSBC, and Wells Fargo Bank. It was Mr. Spitzer’s first foray into consumer banking after probes of the securities, mutual fund, and insurance industries for practices he claimed were abusive.

The banking regulator, in filing its lawsuit, failed “to identify any other federal scheme that strips states of authority to exercise their core sovereign right to enforce their own non-preempted laws,” Mr. Spitzer said in the court papers.

More than 15 consumer groups, including the NAACP Legal Defense and Educational Fund, sought permission from U.S. District Judge Sidney Stein to file an amicus brief opposing the comptroller’s lawsuit.

The consumer groups cited a 2002 U.S. Department of Housing and Urban Development study that suggested black and Hispanic borrowers in New York were more likely to receive costly sub-prime loans. HUD statistics show half of the sub-prime loans in New York City are in black neighborhoods, the groups said.

The consumer advocates also argue that federal data “show a significant racial disparity in mortgage loan pricing by some of the largest OCC-regulated institutions in New York. Black New Yorkers who get a mortgage from JPMorgan Chase, for example, are twice as likely as their white counterparts to receive a high-cost loan,” they stated in their amicus brief.

A spokeswoman for JPMorgan Chase, Calmetta Coleman, said the company would not comment on pending litigation.

In a speech last month to the New York Bankers Association, then-Acting Comptroller of the Currency Julie Williams addressed criticism that the agency’s enforcement is too soft.

“When supervisors identify an issue, we expect it to be fixed, promptly, without having to resort to subpoenas for the information we need or to enforcement action to achieve the result we seek,” Ms. Williams said.