Turkish terrorist Mehmet Ali Agca said yesterday that Soviet secret police "took part" in the attempted assassination of Pope John Paul II, the Italian news agency AGI reported.

It said Agca, who is serving a life prison term for the 1981 shooting of the pope, made the allegation in a surprise meeting with reporters as he emerged from police headquarters, where he had been questioned in another case.

According to The Associated Press, AGI quoted Agca as saying, "I have been several times in Bulgaria and in Syria . . . and in the attack against the pope even the KGB Soviet secret police took part."

It was the first time Agca spoke to reporters about the shooting. Earlier, Italian press reports had said Agca told investigators the plot to kill the pope involved Bulgarians acting under instructions from the Soviet secret police.

AGI said reporters asked Agca yesterday if he knew Sergei Ivanov Antonov, a Bulgarian airline official arrested here on charges of complicity in the shooting. It quoted Agca as replying, "I knew Sergei; he was my accomplice." Antonov has denied involvement in the attack.

Agca spoke with reporters after he was brought to police headquarters for questioning about the kidnaping of the daughter of a Vatican employe. A man who claimed to be the abductor has demanded by telephone that Agca be released.