Cuba opened the nonaligned movement's meeting of foreign ministers here today with a stinging denunciation of U.S. "imperialism" and urged a boycott of Israel and condemnation of its peace treaty with Egypt.

In the latest draft of a document that Cuba proposes to be adopted as a resolution by the 94-member body, Cuba also called for withdrawal of U.S. forces from South Korea and the Indian Ocean and independence for Puerto Rico.

Cuba authored the document as host for the sixth nonaligned meeting of member heads of state that will begin Monday. Its eventual wording, after discussion today and Friday by the foreign ministers and by the summit leaders next week, will determine the international policy consensus of the movement for the next three years.

Despite the attempts of a number of nonaligned countries -- many of them lobbied by the United States -- to tone down the document from a preliminary version circulated several weeks ago, many delegations agreed with the Cuban's contention that the latest draft came out even tougher.

While the issues faced by the 24-year-old organization are not new to it -- imperialism, colonialism, racism, economic equality and weapons control -- the way they are presented every three years tends to reflect the views of the host.

Cuba is calling for "natural alliance" between the nonaligned nations and the Soviet bloc, along with harsh condemnation of the United States.

Other nonaligned members, led by Yugoslavia, say the only alliances natural to the organization are its members ties with each other. They reject ties with either of the big power blocs.

That conflict is expected to be the basis of the biggest battles during the summit. At the same time, what started in 1955 as a meeting among four nations concerned about the dangers of atomic war has grown into an increasingly unwieldy group spanning most of the southern half of the world, all of the Third World and encompassing more than 1.5 billion people.

Outgoing Council of Ministers Chairman A. C. Shahul Hameed of Sri Lanka noted today that "in the early days of the movement, when numbers were small and the major political issues facing the movement were clearcut, the unity of the movement was seldom in question.

"Are we organized amongst ourselves to negotiate the implementation of nonaligned principles in international relations?" Hameed asked. "There are vital global economic issues confronting us all. Can we insure that the nonaligned movement's response to them is more constructive and less declaratory?"

One issue of vital economic concern to many members that do not produce oil is the price of energy. A new section in the draft document, reportedly pushed by Algeria and Iraq, condemns the West's "cheap and irresponsible exploitation of oil extracted from backward and defenseless nations" and criticizes the West for "squandering hydrocarbons" and trying to blame the oil producers.

It has become a question here whether the Third World can embrace both the energy-poor nations devastated by the price of oil and the producer states that have benefitted.

While the plenary meetings of foreign ministers and the four-day summit likely will be devoted to ceremonial speeches, with only an occasional floor fight, the real wheeling and dealing will go on in the hotels, member embassies and local restaurants.

Among the earliest lobbyists when ambassadorial and technical meetings were held at the beginning of the week were delegates of the ousted Cambodian government of Pol Pot.

Host Cuba clearly sides with a delegation sent by the new Heng Samrin government, put into power in Phnom Penh last winter and backed by its allies in Vietnam. So, although the Pol Pot government is still officially on the nonaligned roster, its delegation has not been seated.

In a press release Tuesday, Pol Pot's delegates charged Cuba with "abuse and discrimination" in lodging them at Santa Maria, a beach resort 20 miles away, while the rest of the delegates are in Havana. When they drove in to attend a meeting of Asian nations Tuesday, the delegates said, they were turned away by a Cuban official without explanation.

The nonaligned ambassadors turned the question of which Cambodian delegation to seat over to the foreign ministers, who are now expected to turn it over to the heads of state. Many predict that the seat will remain empty, in effect a victory for the new rulers.

Another procedural question arose on the issue of whether to allow the Philippines nonaligned observer status. Some delegates objected because of the presense of two U.S. military bases in the Philippines. When others questioned the presence of Spain and Portugal at the meetings on similar grounds, they were told those two were "guests" and not observers.

"Unless we nail down the distinction between guests and observers," an Indian delegate dryly observed, "South Africa may apply next."

Despite the document, the Cubans have gone out of their way to describe the summit as "one more step of unity" for the nonaligned movement. A successful summit is considered here to be important to enhance international stature of Cuban President Fidel Castro.

That goal may be a devisive element in the summit, especially if the Yugoslav delegation succeeds in retaining its major leadership role.

Yugoslav representatives have been lobbying busily the delegates warning that Cuba's responsibility as host will make it liable if disunity results.

Cuba's draft document was circulated last night following the arrival of President Tito, 87, the Yugoslavian patriarch of the nonaligned movement and its only living founder since the deaths of Egypt's Gamal Abdel Naser, India's Jawaharlal Nehru and Indonesia's Sukarno.

Looking fit and tanned, Tito was greeted at the airport by Castro.