Paris — The admission yesterday by French Prime Minister Laurent Fabius that French secret agents had sunk a Greenpeace ship in July has dealt a heavy blow to President Franois Mitterrand. ``French secret agents sank this boat. They have been acting on orders,'' Fabius said in a statement read to reporters.
The admission followed the resignation Friday of French Defense Minister Charles Hernu after learning that the head of France's overseas intelligence service had refused to answer questions about the sinking of the ship, the Rainbow Warrior.
The intelligence chief, Adm. Pierre Lacoste, was fired Friday.
Mr. Hernu, a longtime friend and ally of Mr. Mitterrand's, was succeeded by Paul Quil`es, who was minister of urban affairs, housing, and transportation.
Hernu had consistently supported and protected France's armed forces and enjoyed great respect among the military. He also embodied the nation's strong defense posture, which most of France's political parties support.
More important, Hernu's departure -- and the government's admission of guilt -- raises grave questions about Mitterrand's ability to stay in power past next spring when, polls predict, the rightist opposition will recapture a parliamentary majority.
Since the President's term lasts until 1988, the Fifth Republic for the first time will probably have to operate under the delicate balance of a leftist president and a rightist assembly.
Considering the general approval on the right of Hernu's defense policies, analysts had predicted that he might be the one Socialist cabinet member that the new majority might keep on as a measure of consistency during a sensitive time in France's political life.
The loss of Hernu throws fresh doubts on the effectiveness of what the French call a government of ``cohabitation.''
And the prospects of such a government are further threatened, observers say, as new revelations in the Greenpeace affair continues to cloud the Mitterrand presidency and France's image internationally.
One of the President's main sources of strength in a government of cohabitation would be his personal reputation and the prestige of his office.
``I think that cohabitation will be impossible,'' says Philippe Moreau Defarges, professor at the Institute of Political Studies.
``Now [the President] won't have that moral authority any more. . . .
``The King is naked, and it's very serious.''
Observers say that a revelation of the sort made Sunday is likely to trace responsibility straight to Mitterrand, now that the defense minister has fallen. That would make it very difficult for the President to clear his name completely, they say.
It remains unclear when Mitterrand was informed of the French connection to the sinking.
The influential Paris daily Le Mondereported that the President learned of it a week after the July 10 sinking, but waited three weeks -- until press reports began to appear -- before he ordered an investigation.
The Rainbow Warrior sank after explosions that left one crew member, a photographer, dead. New Zealand authorities have charged two French agents with the bombing and newspapers have reported that a second team of French agents was present in Auckland harbor aboard a sailboat shortly before the bombing.
Pressure had been building on Hernu all week as newspapers, including Le Monde, reported that a third, yet unknown, team of French agents had planted bombs on the hull of the Rainbow Warrior while it was docked in the Auckland, New Zealand, harbor last July.
The accounts said that Hernu and top military officials either ordered the mission or at least knew it was in the works.
Hernu issued vigorous denials to the reports.
Hernu repeated his position that French agents had indeed been sent to gather information about Greenpeace's plans to protest French nuclear tests in the South Pacific.
But he insisted that none were involved in the bombing.
Then, Thursday evening, Mitterrand sent a letter to Prime Minister Laurent Fabius saying the press accounts had brought out evidence that their subordinates had withheld.
``This situation cannot continue,'' Mitterrand wrote, ordering the prime minister to make the necessary ``personnel changes.''
Mr. Fabius released his answer to the President Friday. It described Hernu's latest investigation within the defense ministry.
Asked directly whether another team of French agents had been in New Zealand, Lacoste refused to answer Hernu.
The minister then tendered his resignation.
``I know, since last night,'' Hernu wrote in his resignation letter Friday, ``that without any question, officials in my ministry hid the truth from me.''
Lacoste released his letter to Hernu saying that to answer the minister's questions would endanger the lives of some French agents.
``The confirmation of these rumors would only benefit a foreign power and its investigators,'' he wrote.
Just as Hernu issued his resignation, the weekly magazine L'Express reported that the funds for the Greenpeace mission in New Zealand were approved by Gen. Jean Saulnier, Mitterrand's top military adviser.
The one point of strong agreement on all sides is that the story is not over yet.
Commenting on the Hernu resignation, Jean Lecanuet, president of the opposition party, Union for French Democracy, said:
``The act of designating a scapegoat can only appear as a maneuver to slow the establishment of the truth and to hide the real responsiblities.''