Marine Lt. Col. Oliver L. North renewed his legal battle yesterday to block independent counsel Lawrence E. Walsh's investigation of the Iran-contra affair.

In the latest in a series of court hearings, North's attorneys appeared before the U.S. Circuit Court of Appeals for the District of Columbia to argue that Walsh could not legally conduct the grand jury criminal investigation.

The legal wrangling reportedly stems from North's refusal to comply with a grand jury subpoena for a sample of his handwriting.

His attorneys appealed an earlier ruling by U.S. District Court Judge Aubrey E. Robinson Jr. that found a backup Justice Department appointment of Walsh was valid.

Much of the argument centered on whether Walsh was responsible to the attorney general under this backup appointment and whether some of Walsh's assistants, who were appointed before the Justice Department appointment and thus did not take an oath of office, lack authority to go before the federal grand jury investigating North and other figures in the arms deals.

Attorney Barry Simon, appearing for North, told the court, "The independent counsel holds that he is free of the budgetary, hiring and supervisory controls of the attorney general." He argued that Walsh has maintained that he remains outside the Justice Department.

"The independent counsel is not in any way acting as an agent of the executive branch and is not in any way acting under the regulation," Simon said.

However, Paul L. Friedman, an associate independent counsel appearing for Walsh, said the investigation would proceed under the authority of the attorney general if ordered.

Walsh had "accepted the {Justice Department} regulation and consented to the appointment under the regulation," he said.

He repeated earlier assertions that Walsh was entitled to conduct the investigation under both the original Ethics in Government Act appointment and the backup appointment.

Assistant Attorney General James Spears told the court that Walsh was answerable to Attorney General Edwin Meese III.

North, who was fired from the National Security Council last November for his role in selling arms to Iran and diverting the proceeds to aid the Nicaraguan contras, attended the hearing in his Marine uniform, sitting in the packed public gallery flanked by two security guards.

He and his attorneys, Simon and Brendan V. Sullivan Jr., were escorted by more guards out a separate court entrance.