PANAMA CITY, JULY 6 -- Retired colonel Roberto Diaz Herrera agreed today to appear before the attorney general to formally accuse military leaders of corruption -- charges that he leveled publicly last month, touching off a wave of antigovernment protests here.

Diaz Herrera, former chief of staff of the Panamanian Defense Forces, told reporters that an investigation into the charges ordered by President Eric Arturo Delvalle Sunday in a nationally broadcast address probably will be nothing more than a "judicial mound of useless papers, a joke."

He said Delvalle's military-backed government and the judicial institutions serving it are "de facto, illegal, fraudulent and illegitimate" and lack any authority for carrying out an inquiry.

"It is totally irregular to go to testify before the very people whom I have accused," Diaz Herrera said. "There cannot be an impartial judgment {if} the judge is one of the players."

Shortly after he was forced into retirement last month, Diaz Herrera charged that military strongman Gen. Manuel Antonia Noriega, head of the 20,000-man Panamanian Defense Forces and the political power behind the government, rigged the 1984 presidential elections and ordered the murder in 1985 of a key opponent, Hugo Spadafora.

The charges unleashed anti- and pro-Noriega demonstrations that have continued since June 9, and relations between Washington and Noriega have become strained.

Attorney General Carlos Villalaz issued a summons Sunday for Diaz Herrera to appear today for a formal rendering of his accusations. Delivered through church officials, the summons reached Diaz Herrera an hour and a half after his appearance was scheduled.

{Diaz Herrera told The Associated Press that under Panamanian law he had three days to respond to the summons and announced that he would appear at the attorney general's office at 10:30 a.m. Thursday.

{But he said he would go only in the company of his family, "unarmed aides," the Vatican's envoy to Panama and a bishop.

{"I accept going, if I am still alive," Diaz Herrera said.}

Truckloads of riot plice were posted outside the attorney general's office early today, apparently awaiting Diaz Herrera's arrival.

Diaz Herrera said his statements have done permanent damage to Noriega's hold on power.

"There was nothing new in what I charged. Everybody knew, from Arnulfo Arias {the former president defeated in the 1984 elections} to {U.S. Assistant Secretary of State} Elliott Abrams in the State Department, that there was electoral fraud. My statements have been a detonator of the people because it was a military chief who said it.

"The problem is no longer Roberto Diaz Herrera -- just look in the streets . . . . {Noriega} can kill me but he is going to fall. Noriega is no longer a political option in Panama."