PARIS (AP) _ Defense Minister Paul Quiles called the sinking of the Greenpeace ship Rainbow Warrior a ''regrettable affair'' Monday and hoped that New Zealand justice would act reasonably toward two French spies who admitted a role in the bombing of the boat.

Maj. Alain Mafart and Capt. Dominique Prieur pleaded guilty in Auckland District Court earlier Monday to lesser charges of manslaughter and arson after a surprise intervention by the country's chief prosecutor. They are to be sentenced Nov. 22.

The pair had originally been charged with murder and faced the prospect of mandatory life sentences.

A Greenpeace photographer was killed when the ship was sunk by mines in Auckland harbor before it was to lead a protest campaign against France's nuclear test site at Mururoa Atoll.

Charles Hernu resigned as France's defense minister following disclosures that French agents were responsible, and the head of the General Directorate for External Security, an intelligence agency, was fired.

''I've been preoccupied by these two officers since I took up my functions Sept. 20,'' Quiles said on French television.

Asked about reports that New Zealand and France struck a deal to reduce the charges against the two, Quiles replied obtusely: ''New Zealand is a friend of France. Simply, there were several campaigns in New Zealand, campaigns of an anti-French nature, rather shocking. And we have commercial relations with New Zealand which we would like to continue.''

Asked if the French government reminded New Zealand of the commercial ties, he said, ''In discussions between friends, one says many things.''

He called the sinking ''a regrettable affair in which two French officers have been implicated in an operation completely out of proportion with the desired objectives.''

France hopes that New Zealand will expel the two agents after the sentencing, but Quiles cautioned against too much optimism, saying, ''Nothing is settled for now. I hope New Zealand judicial authorities are reasonable.''