More than 1,000 Indians were encamped in Greenbelt Park just outside Washington last night, the final staging point for their ceremonial march on the nation's capital today and eight days of political protests and religious observances.

Participants in The Longest Walk, as the Indians' 2,700-mile, cross-country trek is called, trudged along Route 29 through Howard and Montgomery counties yesterday, converging on Greenbelt Park in Prince George's County in the late afternoon.

At the same time, U.S. Army and Interior Department officials were racing to get extra equipment officials were racing to get extra equipment - field kitchens, water tanks, refrigeration units - to supplement limited facilities in the park.

The Indians' request for logistical support was stalled for several days this week by regulatory red tape unitl the White House gave a go-ahead signal late Thursday. Army officials, with less than 24 hours to work in, said yesterday it was unlikely they could get all the requested equipment into the park by last night.

Meanwhile, the District of Columbia girded for the Indians' procession into the city today and for a series of rallies, demonstrations and protest marches on the Capitol, White House, Supreme Court and the FBI building next week. The Indians are protesting alleged discrimination and legislation and abolish the traditional trust relationship between Indians and the U.S. government.

The Indians, a loose coalition of more than 100 tribes and organizations from across the country, are scheduled to march down Georgia and Arkansas avenues and 16th Street NW this morning for a midday rally in Meridian Hill Park (also known as Malcolm X-Park).

The procession, headed by Indian spiritual leader Ernie Peters carrying a sacred pipe packed with ceremonial tobacco, will then continue down 16th Street, pass the White House and finish up on the Washington Monument grounds.

While the bulk of participants are expected to get and sleep each night at the Greenbelt Park encampment and come into the city each day by bus shuttle service for next week's political actions, some 200 to 300 elders and religious leaders will remain in an enclosed "spiritual camp" in West Potomac Park near the monument grounds. They will conduct a continuous four-day vigil, organizers said, with a fire burning constantly on a special alter surrounded by a ring of 20 to 30 ceremonial tepees.

The camp will be enclosed by a double snow fence, and organizers said admittance by the public will be limited to certain times and occasions.

Mayor Walter E. Washington proclaimed today as "Longest Walk Day" and officially welcomed the Indians yesterday when he presented their leaders with a symbolic key to the city.

While cordiality and cooperation prevailed in much of official Washington, security was beefed up at the Interior Department, security was beefed up at the Interior Department's main building at 18th and C streets NW yesterday. Officials said they have no specific indication of possible trouble but are mindful of the Indian takeover of the Bureau of Indian Affairs building here in 1972 during the so-called Trail of Broken Treaties, a political action march similar to The Longest Walk and with some of the same leadership.

Longest Walk leaders, including members of the militant American Indian Movement who participated in the 1972 BIA takeover, have repeatedly stressed the peaceful and religious intent of The Longest Walk program.

After a series of last minute negotiations, the Interior Department yesterday arranged through the District government for Metro to provide about 15 buses for the Greenbelt-downtown Washington shuttle service, thus solving one of the toughest logistical problems of The Longest Walk.

Medical and extra sanitation facilities at both Greenbelt Park and West Potomac Park have already been arranged, government officials said.

Some $15,000 has been donated by the United Methodist Church for food purchases. Longest Walk organizers said they also hope to raise $25,000 through the National Council of Churches and unspecified additional amounts through a benefit concert at the Capital Centre on July 23 and a benefit performance of the Indian play "Black Elk Speaks" at the Kennedy Center Sunday night.

These sums would be used to help pay travel expenses for Indians going home after The Longest Walk is over, organizers said.