Mounting evidence that French secret service agents sabotaged the flagship of the Greenpeace environmental movement has created a political headache for President Francois Mitterrand's Socialist administration.

Suspicions of French involvement in last month's sinking of the Rainbow Warrior in the New Zealand port of Auckland were bolstered this week by the issuing of international arrest warrants for three suspected members of the French secret service, the DGSE. Two other alleged French undercover agents have been formally charged in New Zealand with arson and the murder of a Rainbow Warrior crew member killed in the explosion.

"The DGSE is indeed responsible for the attack against the Rainbow Warrior," ran the headline in today's editions of the respected Paris newspaper Le Monde, summing up what has now become the consensus in the French press.

The Rainbow Warrior was severely damaged by two underwater explosions a few minutes before midnight on July 10 -- just as it was about to set sail for the French nuclear test site of Mururoa Atoll in the South Pacific. A converted fishing trawler that has been used to champion a wide variety of environmental causes, from the preservation of whales to the prevention of oil pollution, the ship was the leader of a flotilla of vessels protesting French nuclear policies.

With no one in the French government bothering to deny allegations of some kind of DGSE involvement, attention is now focusing on who ordered the sinking of the Greenpeace ship. Theories advanced so far in the French press have ranged from an elaborate plot hatched by the president's own aides to a bungled operation organized by a right-wing faction of the secret services.

In an apparent attempt to prevent the affair from developing into a French Watergate, Mitterrand last week entrusted an independent inquiry to a respected Gaullist politician, Bernard Tricot. Mitterrand promised to publish the findings of the inquiry and to "severely punish" any official found to be involved in a terrorist act.

Among the 100 pieces of evidence so far collected by New Zealand police are a rubber dinghy and two white-painted oxygen bottles with French markings found on a beach near Auckland shortly after the explosion. Local residents said the dinghy had been abandoned by the owners of a camping van who left the beach after being mistaken for burglars.

Three days after the sinking of the Rainbow Warrior, police arrested a French-speaking couple with Swiss passports in the name of Alain and Sophie Turenge as they were returning a rented camping van similar to the one seen on the beach. The passports turned out to be false. After being formally accused of murder and arson, the "Turenge" couple refused to make any statements.

Subsequent inquiries by the New Zealand police focused suspicion on another group of Frenchmen seen around Auckland shortly before the explosion: the crew of a yacht, the Ouvea, rented in the French Pacific island of New Caledonia. The Ouvea -- along with three members of its four-man crew -- has since vanished.

Although the French Defense Ministry has refused to comment publicly on the case, it now seems virtually certain that "Sophie and Alain Turenge" are French undercover agents. Telephone numbers found in an address book in their possession appear to belong to the DGSE, and several French news organizations have identified them as a captain and a major in military intelligence.

The weekly magazine L'Express today reported that "Sophie Turenge" was in fact Capt. Dominique Prieur, 36, a member of the DGSE's special "action section." It said that friends had recognized her picture in the newspapers following the arrest of the "Turenges."

There is still some doubt about the exact nature of the "Turenges' " mission in New Zealand. The most charitable explanation for their presence in Auckland is that they were merely gathering information on the Rainbow Warrior before its departure for Mururoa.

A report last Saturday by the state-run radio station, France Inter, claimed that the crew member of the Rainbow Warrior killed in the explosions, Fernando Pereira, belonged to a pacifist group with close ties to the Soviet Union. It also maintained that the ship was carrying powerful transmitting equipment capable of relaying to foreign countries sensitive information about France's nuclear testing program.

Spokesmen for Greenpeace have denied these allegations as well as reports that the Rainbow Warrior carried highly sophisticated equipment capable of precise monitoring of French tests of neutron bombs.

The more damaging hypothesis for the French authorities is that the "Turenges" were working with the crew of the Ouvea to sabotage the Rainbow Warrior. The New Zealand authorities are reported to have evidence of links between the two French groups, including some remarkable coincidences in their itineraries before the bombing.

In a press conference in Paris today, Greenpeace chairman David McTaggart refrained from directly accusing the French government of ordering the sinking of his organization's flagship. But he said it was quite clear that the "Turenges" were in the pay of the French government.