A Polaroid snapshot showing kidnapped former premier Aldo Moro apparently unharmed was released yesterday by Italy's Red Brigades terrorist group, which said that the influnential Christian Democratic leader would be tried by a people's court, but made no specific demands for his release.

The black and white photo showed Moro, in shirtsleeves and looking wan and tired but apparently well, seated in front of a wall decorated with the Red Brigades symbol - a five-point star inside a circle.

It was accompanied by a two-page typewritten communique in which the Red Brigades officially claimed responsibility for Thursday's bloody ambush here in which Moro was seized and five of his police body guards were murdered.

The release of the photo more than 48 hours after the kidnapping was greeted with relief by Italian politicians and many ordinary Italians, who had feared for Moro's life or that he might have been hurt in the hail of as many as 70 bullets fired during the kidnapping.

Premier Giulio Andreotti, whose new Communist-supported Christian Democratic government won an over-whelming vote of confidence Thursday, announced meanwhile that the massive manhunt for Moro and his captorswould be stepped up with help from Rome-based army units and appealed for full cooperation, from Italians.

The communique, left for a Rome reporter at a prearranged spot, referred to Moro as the "unquestioned theoretician and strategist of the Christian Democratic regime" and accused him of being the "Political godfather" of world imperialism in this country.

The absence of specific demands in this first message from the kidnappers other than phone calls made it clear that earlier calls demanding the release of 15 jailed terrorists now on trial in Turin in exchange for Moro's life were hoaxes and led police and others to hope that the 61-year-old politician eventually may be released unharmed.

A high-placed Italian intelligence source said that in four previous political kidnappings by the Red Brigades in 1973 and 1974, the victims - a right-wing trade unionist, two executives from Alfa Romeo and Fiat, and a Genoa judge - were all released after several days or weeks in captivity.

He saw as significant the fact that the terrorists two-page statement discussed separately Moro's "Trial" and the Turin trial of the terrorists. The communique called the Turin trial a farce and said "let it go on," thus contradicting the widespread assumption here that the immediate purpose of Moro's kidnapping was to force a stop to the judicial proceedings against several of the Red Brigades "founding fathers."

The intelligence source said that it was unlikely that police, who believe Moro is hidden somewhere in or near Rome, would succeed in locating the hideout. "It is like looking for a needle in a haystack," he said, estimating that Moro might be held for as long as two or three weeks before being released.

"If they made a point of not killing him immediately, then their goal can be only ransom and exchange or ideological theater," the source said.

Several thousand apart*ments have been searched so far in a radius extending several miles around the Monte Mario residential neighborhood where the ambush took place. Police at roadblocks have searched hundreds of cars.

In Rome, where thousands attended the funeral service at the San Lorenzo Basilica of the five slain policemen, a 32-year-old man, Gianfranco Moreno, was jailed in connection with the kidnapping. Unofficial reports said he might be implicated in the preparation of the crime rather than its execution.