SALONICA, Greece (AP) _ Thousands of people trekked to a small church in northern Greece Sunday to catch a glimpse of gold, frankincense and myrrh revered by Orthodox Christians as the gifts given to Jesus by the Three Wise Men.

Three small silver caskets from the Monastery of St. Paul on Mount Athos, each containing a gold basket holding several plum-sized pellets of dark frankincense mixed with myrrh, went on display for the first time in 500 years at the newly built church of Saints Cyril and Methodius.

''A stream of people trooped through the church all morning to kiss the glass surrounding the gifts,'' a photographer, Yiannis Kyriakides, told The Associated Press.

According to Orthodox Church histories, the gifts of the Magi were presented to the monastery in 1453 by the mother of Sultan Mehmet, who conquered Constantinople (modern Istanbul) that year.

The treasures were brought in 1203 from Jerusalem to Constantinople, capital of the Byzantine empire, by order of Emperor Arcadius, the histories relate.

According to the Gospel of St. Matthew, the Magi presented the infant Jesus with ''gifts, gold and frankincense and myrrh.'' The fragrant incenses frankincense and myrrh originated from a resin exuded by a rare tree in the Middle East.

The caskets arrived Sunday in Salonica under heavy guard from Mount Athos, a centuries-old autonomous monastic community where women are banned. The caskets will remain on display until Jan. 3.

''They're being displayed in this church to commemorate 1,100 years since the death of St. Methodius, and also the 2,300th aniversary of Salonica's founding,'' said Father Ioannis, a priest at the church.

Saints Cyril and Methodius, both born in northern Greece, brought Christianity to the Slavs of Eastern Europe.

''The frankincense and myrrh have combined over the centuries and now exude a very delightful smell,'' Father Ioannis added.

But some modern Orthodox theologians say there is no proof the treasures are genuine.

''There is no historical evidence, only mystical and devotional traditions about the gifts of the Magi. Their history comes down to us mostly from monastic traditions,'' said Professor George Moustakis, who teaches theology at the American College in Athens.

The Christmas display will help ease disappointment caused by the monastic community's failure to stage a promised exhibit of treasures from Mount Athos in time for the city's anniversary celebrations.

A senior Greek Foreign Ministry official said last week that the exhibit had been postponed until sometime in 1986.

The 20 monasteries on Mount Athos have rich collections of religious art that go back at least 1,000 years and include unique icons, jeweled gospels, and illuminated manuscripts.