The diamonds that Central Africa's deposed emperor Bokassa gave to French President Valery Giscard d'Estaing when the two men were telling each other that they were the best of friends came back to haunt the French Leader last week.

The French presidential palace said this weekend to general surprise that it had obtained copies of letters from Bokassa confirming the authenticity of a recent long-distance telephone conversation in which he personally confirmed for the first time the press allegations about his gift of gems to Giscard and his family.

The French president has never actually denied receiving the diamonds, only that they were not worth the large amounts that the press said that they were.

The phone conversation is the first time that Bokassa has been able to speak out directly in a year of virtual house arrest in the Ivory Coast in West Africa. The conversation with the weekly Canard Enchaine -- which first carried the allegations about Bokassa's diamonds -- and the subsequent fallout have revived an affair that seemed to have petered out despite the approach of Giscard's campaign for reelection next spring.

"You cannot imagine what I gave to that family, I assure you that you can't imagine," the Canard quoted Bokassa as saying.

The ex-emperor said he had given diamonds to Giscard three times and to his wife Anne-Aymone once in the presence of the Central African Cabinet.

Bokassa said Giscard and his cousins had been coming to hunt elephants twice a year in Bokassa's native village and had stayed at his home there.

The Elysee's unexpected admission that it has copies of the letters seemed to be linked to a counteroffensive designed to show that Bokassa is unsavory, mentally unbalanced and thirsting for revenge since French paratroopers occupied his capital and installed a new ruler a year ago.

The progovernment weekly magazine Figaro yesterday revived charges of cannibalism against Bokassa and quoted a former French adviser to the emperor as saying that he had a Hollywood-style swimming pool full of crocodiles in which he used to throw condemned prisoners to entertain privileged guests at his palace.

The adviser quoted the emperor, deposed in part because of the international outcry over allegations that he directed the massacre of schoolchildren, as saying that he had killed far fewer children than France's law legalizing abortion.

The Elysee spokesman said he could not explain how the Elysee had gotten copies of the letters addressed to the Canard Enchaine. Claude Angeli, the weekly's new editor, said it had received hand-delivered photocopies, not originals.

The Elysee did not deny an unattributed claim by the weekly magazine L'Express yesterday that the hour-long conversation between Bokassa and Angeli in Paris on Sept. 9 was taped by a French government listening service. Angeli said there were other "interesting" statements by Bokassa that the Canard will publish on Wednesday.

The Canard said that Bokassa had promised to call back the next day for another talk, but that he never did. It charged that his phone had been cut. Several articles asked how Bokassa had been able to free himself of his strict surveillance long enough to call.

Bokassa told the Canard that he has been unable to talk to the press because Giscard forbade it.

The French press often said that Bokassa is, in fact, under the control of French intelligence services. French reporters who have tried to approach Bokassa in the Ivory Coast have been deported, including a Canard reporter Sept. 12.

The Ivory Coast is not the exclusive hunting ground of intelligence men loyal to Giscard, however. It still is considered by many to be the turf of president Charles de Gaulle's old spymaster, Jacques Foccart, who was dismissed by Giscard.

The colonel who headed the action service of French foreign intelligence, Alain de Gaigneron de Marolles, was dismissed this month, and there is intense speculation that it was because he was siding with the Gaullist clan in the Ivory Coast.

Gaullist Party leader Jacques Chirac noted, "I'm one of the rare French politicians who held an important post and never met Bokassa or went to Central Africa or dined with him."

Chirac recalled that he had always refused to comment about the diamonds, but added, "One the other hand, I'm very astonished by the silence of certain editors-in-chief over this affair." He was referring to the virtual blackout in the progovernment press, especially the three conservative Paris papers owned by press lord Robert Hersant.

Bokassa referred at length to the growing affair within the affair -- the imprisonment here since May 10 of Roger Delpey, a writer-adventurer who was working on a book based in part on 187 documents given him by Bokassa. w

Delpey is a former Gaullist Army officer who wrote a bestseller about the French war in Indochina, but mutined against De Gaulla over Algerian independence.

Bokassa said he also gave Delpey a number of signed blank sheets to send letters for him to other African chiefs of state and that he had in effect made him his agent in Europe.

Delpey was arrested while emerging from the Libyan Embassy in Paris and was indicted by the state Security Court, an exceptional tribunal formed during the Algerian war, for "intelligence with the agents of a foreign power of a nature to damage the diplomatic situation of France." A prosecutor said today that Delpey was seeking Libyan financing for an anti-French campaign of "technical disinformation."

"Delpey's lawyer, Roland Dumas, said in a telephone interview yesterday that the only question his client had been asked in connection with the charge was, "Don't you admit that your activities were of a nature to harm the president of the republic?"

Dumas said that nobody is currently being questioned and that the investigating magistrate has refused to call defense witnesses, including Bokassa, Col. De Marolles and the Libyan diplomats with whom Delpey spoke.