The French government called today for the early release of two secret agents sentenced by a New Zealand court to 10 years' imprisonment for the sabotage of a ship belonging to the environmentalist organization Greenpeace.

The agents, Maj. Alain Mafart and Capt. Dominique Prieur, were both convicted of manslaughter and criminal arson after pleading guilty to involvement in the bombing of the Rainbow Warrior in the port of Auckland on July 10. One crew member was killed. The French government has acknowledged that the agents acted under orders with the aim of forestalling protests against French nuclear tests in the South Pacific.

In a radio interview, Defense Minister Paul Quiles hinted at political negotiations between France and New Zealand for the release of the agents by saying that the "Greenpeace affair" had now entered a "new phase."

"The French government will do everything in its power so that the French officers can come back to their country as rapidly as possible," he said.

Negotiating the release and deportation of the two agents is politically important for France's Socialist government, which faces crucial legislative elections next March. The prolonged detention of the agents, who at first claimed to be a honeymooning Swiss couple, would make the government vulnerable to renewed attacks by the right-wing opposition and discontent within the armed forces.

Political sources here said that France is willing to offer generous compensation to both New Zealand and Greenpeace if the agents are released. French officials also have held out the prospect of more favorable conditions for the importation of New Zealand lamb and butter by the European Community.

The Greenpeace affair has largely dropped off the front pages of French newspapers since September, when it provoked the resignation of defense minister Charles Hernu and the dismissal of the head of the secret services.

Passing sentence on the two French agents this morning, New Zealand Chief Justice Sir Roland Davison said the prison terms were intended "to give a clear warning to persons such as the defendants and their masters that terrorist-style actions will provoke stern reaction and severe punishment."

Interviewed by telephone from prison, Prieur said she was not a "terrorist" but "a captain in the French Army who did what I was told to do."

Prieur, 36, whose role in the sabotage is believed to have been one of logistical support, also suggested that premature public pressure from France on New Zealand could have contributed to the severity of her sentence.

"I wonder if the sentence today wasn't caused by the pressure that has been exerted already, perhaps by the media, perhaps as a result of mistakes from one quarter or another," she said.

Two weeks ago, New Zealand Prime Minister David Lange angrily denied suggestions by French politicians that the two governments were already negotiating a solution that would lead to the release of the two agents. The speculation followed a decision by New Zealand authorities to drop murder charges against the couple in return for guilty pleas to the lesser crime of manslaughter.

A New Zealand defense lawyer, Gerald Curry, also pleaded for the two agents to be expelled from the country so that they would not be a "burden on the taxpayer." He drew laughter from the courtroom when he praised Mafart's concern for the "quality of the environment" and his interest in the preservation of whales.

The defense counsel said that Mafart, who belonged to the action division of the French secret service, had devoted much of the past four months in prison to a study of New Zealand poetry. Prieur, he added, had kept herself busy cooking, knitting and making jam.

Greenpeace chairman David McTaggart said he was disappointed by the sentences, The Associated Press reported. "The other agents who were involved, as well as Hernu, should have been in the dock today," he said.

In France, there are signs of a political comeback by Hernu, who was officially blamed for both the sabotage and the subsequent cover-up. Last month, Hernu was selected to head the Socialist Party's list of candidates in the southeastern Rhone region.

Hernu, who has received tens of thousands of letters of sympathy, told a television interviewer earlier this week that he could be a future candidate for president if the Socialists did well in the Rhone.

At a press conference yesterday, President Francois Mitterrand refused to go into detail about his conversations with the former defense minister after the sinking. Senior French officials have claimed that Hernu deliberately withheld details about French involvement in the sabotage from the president for two months despite a political friendship that goes back two decades.

Asked how he felt about the former defense minister now, Mitterrand replied: "Hernu was, is and will be my friend for a long time to come."