A year after it was warned that it might be violating federal law, the Securities and Exchange Commission is still breaking the law by destroying records of closed enforcement cases, a lawyer in the agency’s enforcement division has alleged.

In addition, the purging of files has involved a wider range of investigative documents than previously reported, according to a signed statement by the enforcement lawyer.

The new allegations are contained in a statement dated Tuesday by Darcy Flynn, a longtime SEC employee involved in managing records for the enforcement division.

Flynn’s lawyer, Gary Aguirre, sent the statement and an accompanying narrative to SEC Chairman Mary L. Schapiro and SEC Inspector General H. David Kotz. Aguirre also addressed copies to several lawmakers, calling on Congress to step in.

Flynn is under “standing orders to direct the destruction of records” that the SEC is legally required to preserve, Aguirre wrote.

A year ago, after Flynn first alerted it to a potential problem, the National Archives, overseer of federal record-keeping, asked the SEC to explain the apparently unauthorized destruction of government records. The SEC told the National Archives that it was preserving the records then in question while it worked to sort out the issue.

SEC spokesman John Nester declined to comment Tuesday except to say that the SEC is reviewing Aguirre’s letter.

The SEC is responsible for policing Wall Street and making sure publicly traded companies don’t dupe investors.

The purging of SEC records, Aguirre has argued, could make it harder to hold the agency accountable when its staff decides to drop probes of alleged wrongdoing.

Anne Weismann, chief counsel at the advocacy group Citizens for Responsibility and Ethics in Washington, expressed a similar view. “To say it’s troubling is an understatement,” Weismann said. “If the SEC itself is acting in an illegal way, then we can have no confidence that it is effectively . . . policing the industry it is charged with policing.”

Flynn became involved in records management early last year. He soon became concerned the SEC was destroying records improperly, his lawyer has written.

Two months ago, Flynn’s lawyer reported his original allegations to Sen. Charles E. Grassley (R-Iowa), invoking whistleblower protection. Last month, Grassley made those allegations public.

In his July letter to Grassley, Aguirre focused on an SEC directive involving records of MUIs, or “matters under inquiry,” an early step in the investigative process. The SEC had long directed its staff to dispose of records obtained in MUIs when it closed those files without advancing to an official investigation, the agency has confirmed.

But in the material addressed to SEC officials and lawmakers Tuesday, Aguirre and Flynn said the SEC is still discarding records improperly, including records of formal investigations.

Enforcement division policy results in the destruction of about 75 percent of the documents the staff generates or receives in formal investigations, Flynn wrote. Of those, the SEC should be keeping about 70 percent, Flynn wrote.

Without legal justification, the enforcement division has given its staff a green light to discard all internal e-mails when investigations are closed, Flynn wrote.

Most of the case documents produced by the staff are currently being destroyed unless they are considered to be “formal memoranda,” Flynn wrote.

“These are matters which require immediate attention,” ­Aguirre wrote.

The SEC should “put a freeze on the current practice of destroying documents after the completion of a formal or informal investigation” until the National Archives, which oversees the preservation of government records, has approved the process, ­Aguirre wrote.

In an Aug. 27, 2010, letter, the SEC told the National Archives and Records Administration that it had instructed its staff to preserve “all MUI records.”

“The documents subject to this hold include any correspondence, interagency memoranda or other documents supporting a decision not to open a formal investigation,” the SEC said.

When Flynn’s original allegations were made public last month, Nester, the SEC spokesman, confirmed that for years the agency had directed its staff to dispose of records obtained in connection with MUIs if the agency decided to close those inquiries without a full-fledged investigation. But he said the agency changed that policy last year.

In his letter Tuesday, Aguirre said the SEC chairman “may be responsible for some of the current violations” for failing to obtain National Archives permission to get rid of documents.

The SEC’s long-standing “Records Retention Schedule,” a set of standards approved by NARA, says that investigative case files must be preserved for 25 years. Documents not listed in the schedule must be preserved until the National Archives approves a timetable for their destruction.

The standing order to destroy documents “puts Mr. Flynn on the horns of a dilemma,” Aguirre wrote.