The 'living treasures' of New Zealand.

After King Tut, the treasures from the Vatican, the gold icons of Russia, and the bronze age artifacts from China, this year the Maoris are coming to America. ''Te Maori'' (the Maoris), which will open at New York's Metropolitan Museum of Art Sept. 10, is the first comprehensive exhibition of Maori art to be mounted outside New Zealand.

The culture of the Maoris, the brown-skinned indigenous people of New Zealand , is more than 1,000 years old. But this is the first time Maoris have agreed to a selection of their art leaving the country and being shown in public.

The reason is that, to the Maori, his classical artworks are ''living treasures.'' The pieces are an integral part of tribal life and as such are traditionally not allowed out of the tribal area.

Organizers here say it took seven years of negotiations to persuade the Maori people to allow the exhibition to be mounted. They finally agreed, after a long series of meetings with various tribal groups, when elders decreed that their art must be shared with the rest of the world if it is to remain a creative force.

Americans will see 176 pieces in stone, wood, and bone ranging in date from about AD 1000 to 1880, many featuring elaborate carvings.

''The exhibition comprises some of Maoridom's most sacred and most valuable taonga, or treasures,'' says Prof. Sidney Mead, head of Maori studies at Victoria University of Wellington, and editor of the book and catalog that will accompany the exhibition.

The exhibits range from tiny fishhooks to a 14-foot-high carved gateway, which until 1845 stood as part of a palisade on the foreshore of Lake Rotorua in the central North Island. The site, Pukeroa Pa, was a major village of the Ngati Whakue tribe, and the gateway features a realistic tattooed face mask which has been graphically reproduced as the logo of the exhibition.

There are pendants, adzes (tomahawks), meres (fighting clubs), and burial chests. Also included are the intricately carved prows and sterns of canoes - the Maoris' traditional vessels in which, legend has it, they first migrated to New Zealand from their ancestral homes in the Society Islands of the South Pacific.

An 800-year-old necklace of sculptured whale teeth that will be shown - found in a young girl's grave - is similar to pendants in ivory, stone, and wood found in other parts of the Pacific.

One historic exhibit is a set of carved wooden panels from a storehouse; they were discovered in 1912 after being hidden for nearly 100 years in a beach cave at Te Kaha, on the North Island's East Cape. They had been hidden during a series of intertribal wars fueled by the white man's introduction of the musket to the Maoris.

After four months at the Metropolitan in New York, the exhibition - which is being indemnified by the United States government to the tune of $30 million - will be shown at the St. Louis Art Museum from Feb. 22 to May 26, 1985, and the M. H. de Young Memorial Museum of Fine Arts, San Francisco, from July 6 to Dec. 1, 1985.

Only on its return home in early 1986 will New Zealanders get a chance to see the finest collection ever assembled of the art created by the people who founded their country.

Americans will find that ''Te Maori'' is not just an exhibition, but a happening. At least 50 Maori elders will take part in a sacred ceremony at each of the three exhibition openings in New York, St. Louis, and San Francisco.

The ceremonies, which must take place at dawn, are primarily cleansing rituals involving prayers for the safety of the pieces while they are on show and their eventual return to tribal lands. Different tribes from across New Zealand will take part in each ceremony so that all are represented.

''The people are part and parcel of the exhibition, caretakers of their sacred heirlooms,'' says Sonny Waru, an elder from the North Island province of Taranaki.

''They are the living embodiment of our ancestors. We must guard them,'' he adds.

Says Professor Mead: ''It is right that the Maori people should be involved. We want to ensure that visitors to the exhibition are aware of Maori people as well as their art. We want them to appreciate that the Maori people are alive and that our culture is a living one.''

The exhibition also includes a 71/2-foot-long door lintel which ethnologists regard as one of the finest examples of Maori carving. It depicts seven figures carved on a background of interlocking spirals. It was thought to be part of a house built in 1850, and was unearthed in 1919.

Many of the carvings, including ''god sticks,'' which marked the dwelling places of tribes' guardian spirits, were made with stone tools long before the pakeha (white man) introduced metal implements.

Piri Sciascia, chief administrator of the exhibition, recalls the years of negotiation with Maori elders to get it mounted. ''Some discussions were long and complex, including deep spiritual concepts,'' he says.

''Many times we were called to account and to justify why we should let our taonga leave our shores.

''I think in the end the majority of our elders consented because they could see that ''Te Maori'' would be a great boost to our mana (prestige, influence), both here in New Zealand and in the United States.''