NEW YORK (Reuters) - New York Attorney General Letitia James is investigating whether Capital One's proposed takeover of Discover Financial Services ( DFS ) violates the state's antitrust law.

In court filings on Wednesday, James asked a state judge to issue a subpoena to Capital One in connection with her probe.

She said a merger could have a significant impact in New York, with effects "particularly felt by the often vulnerable New Yorkers with subprime credit scores."

(Reporting by Jonathan Stempel in New York)