The legal panel of a fact-finding board investigating the assassination last year of Philippine opposition leader Benigno Aquino has submitted a report implicating 18 military personnel and one civilian in a murder conspiracy and a subsequent cover-up.

The report by the board's lawyers is the most important of 11 submitted so far to the five-member panel for consideration in writing its long-awaited final report on the murder of Aquino, a former senator and political rival of President Ferdinand Marcos. One of the five board members, who asked not to be identified, said the lawyers' 479-page submission would be the "basis" for the board's final report.

While the lawyers' account of the facts in the case is expected to be included in the main body of the final report, the conclusions and recommendations deriving from them remain under discussion by the five panel members.

It is still unclear what these will be and when they will be issued, board lawyers said.

One board member said the debate might go unresolved. He said the board's final report could also include a dissenting opinion.

The lawyers' report has not been released officially yet, but has been referred to by board sources.

A copy was made available today by a board official.

The legal panel describes its report as a "narration of the facts" surrounding the assassination of Aquino on Aug. 21, 1983, when he returned to Manila from three years of self-imposed exile in the United States and was escorted off a plane by military guards.

The lawyers' report names Gen. Fabian Ver, the armed forces chief of staff and a trusted confidant of Marcos, as a "participant" in the conspiracy surrounding Aquino's murder.

It cites testimony before the board during its 10-month investigation that Ver ordered the implementation of a plan supposedly meant to secure Aquino on his arrival at the Manila International Airport.

The lawyers' report does not say Ver actually ordered the assassination, but it cites circumstantial evidence that it says indicates he had a role in the conspiracy.

The nature of Ver's role has been the key issue in the debate among the board members about the extent of the conspiracy, according to senior board officials.

Board officials have said all five members agree that Aquino was shot by one of his escorts as part of a military conspiracy.

However, the head of the fact-finding panel, former appeals court justice Corazon Agrava, reportedly has refused to name Ver as a participant in the conspiracy.

In a recent interview published by a local weekly, Ver has denied involvement in the Aquino assassination. Ver also has said that he would not resign as chief of staff if the board blames the murder on the military.

"Of course not," he was quoted as saying. "I will not, I will not. I had nothing to do with it. I had nothing to do with it. I'd rather be cleared also."

In the interview, Ver repeated the military's and Marcos government's version that Rolando Galman, a gunman acting on behalf of communist rebels, killed Aquino. Galman was gunned down on the Manila Airport tarmac by security agents immediately after Aquino was shot.

The security men, who had been escorting Aquino from his plane, testified that Galman had penetrated a security cordon of 1,199 soldiers, but a lawyer for Galman's family has charged publicly that Galman was merely a "fall guy" set up by the military.

The report of the board's four lawyers said that one of the two escorts shot Aquino on a stairway leading from a passenger tube connecting Aquino's China Airlines plane with the airport terminal.

The report cites the secret testimony of a Philippine Airlines technician who was on the tarmac at the time of the murder and said he saw Aquino shot while on the fourth step of the stairway by one of the escorts, whom he could not identify positively.

The report described Ver's role in 33 pages, calling portions of his testimony before the board "illogical and untrue" and even "absurd." Specifically, it criticizes his contention that the military made no attempt to monitor Aquino's return to Manila via several Asian capitals.

The lawyers' report describes the plan to secure Aquino, called "Op Plan Balikbayan," or "Operation Plan Homecoming," as "elaborate plans ostensibly geared towards protecting the life of Sen. Aquino that were in fact designed to camouflage the taking of that life."

The report says that most of its evidence about the military conspiracy is circumstantial, but insists that it is more than adequate to prove a conspiracy.

The report says: "There can be no doubt that a conspiracy has been indubitably established by proven circumstances . . . ."

The only civilian mentioned in the report is a businessman reportedly involved in picking up Galman from his home four days before the assassination.