The Marine Corps wants "multifaceted or complex" congressional questions about Lt. Col. Oliver L. North in writing before they will be answered, according to a letter sent last week by the Marine commandant to House Armed Services Committee Chairman Les Aspin (D-Wis.).

And, Gen. A.M. Gray added, this policy was not initiated because of any agreement between the Marine Corps and North's attorney, Brendan V. Sullivan Jr.

In late October, an aide to Aspin telephoned the Pentagon to ask about North's job status at Marine Corps headquarters. He got no immediate reply, according to congressional sources. In a later conversation, the sources said, Aspin's aide was told by a Marine Corps legislative liaison that someone at headquarters, at the "request" of Sullivan, had adopted a policy that congressional staff queries on North would have to be submitted in writing before they could be answered.

At least one other congressional staff inquiry on North was told the same, sources said.

Aspin, a member of the House Iran-contra investigating committee, sent Gray a blistering letter Dec. 14 saying he was "at a loss to understand how and why a civilian attorney has gotten control over congressional communications with the United States Marine Corps on any matter, let alone matters such as these that are not even tangential or peripheral to the potential legal problems of his client . . . . "

Aspin added that he was "astounded" that the Marine commandant "would acquiesce in such a development" and asked that he "act swiftly to see that it is brought to an end."

Gray, in his Dec. 24 response, said it was "simply not the case" that the policy was an accommodation to Sullivan. "Civilian attorneys do not, and will not, have any input into Marine Corps policy as long as I am commandant of the Marine Corps," he wrote.

Instead, he said, his staff "has responded orally over the past year to a number of such inquiries," but "from time to time . . . we have asked a congressional staff member to submit a written request if the inquiry involved a multifaceted or complex matter."

Congressional staff members are occasionally asked by Pentagon officials to put questions in writing, "but usually only when some corporate proprietary or other sensitive matter is involved where the giver of information needs some protection for the disclosure," a Capitol Hill defense expert said yesterday.

"Classified material is often requested and given over the phone, but not in great detail," he added.

The original Aspin staff question last October sought to determine North's current job. It was expanded in subsequent calls to seek all North's duty assignments since he left the White House in November 1986 and returned to Marine headquarters, and later included a query on when North would be eligible for retirement.

In his letter demanding the policy be changed, Aspin said he had "instructed the committee staff to resubmit the questions by telephone to your legislative liaison office next week."

Gray, in his response, said that since the original inquiry involved "three separate questions, my staff properly determined, in accordance with our policy, that the request should be in writing."

In his letter, Gray described North's assignment as a plans officer at Marine headquarters, an assignment he has held since leaving the White House.

The added Aspin question, the date North would be eligible for retirement, was given as April 24, 1987, by Gray in his letter.

The third question attributed by Gray to Aspin's staff was the date North would be "in the primary zone for promotion to colonel." An Aspin aide said yesterday this question "must have been asked by some other congressional staff."

The date, Gray reported to Aspin, was fiscal 1989.