Former Cambodian head of state Prince Norodom Sihanouk arrived here tonight to plead his country's case before the U.N. Security Council and said the world faces a potential big power clash over the Indochina conflict.

The drive by Vietnamese troops and Cambodian rebels that wrested control of the country from the Pol Pot government "is a danger not only in Asia but from Asia to the world," Sihanouk said during an airport press conference before departing for his hotel.

"The U.S. has said that for the time being we must put aside the question of human rights because there is a much more urgent problem to solve," Sihanouk said. "The problem of peace and stability of the big powers."

"If you do not solve this immediately, you will have a more difficult and more complicated situation," Sihanouk continued. "China may one day intervene to help us regain our national integrity. So the Soviet Union may intervene on the side of the Vietnamese."

Sihanouk said the Vietnamese were responsible for the takeover and that therefore the Pol Pot regime remains the legal government of Cambodia. The Pol Pot administration, he added, was the only government supported by the people, one that improved the life of the poorest classes of the country.

Sihanouk, who flew here from Peking, said that so far China has been asked only for material assistance and not to intervene with troops, although some 19,000 Chinese military advisers are still believed to be in Cambodia, apparently caught up in the lightning Vietnamese-backed invasion that captured Phnom Penh this past weekend.

During a stopover in Tokyo, Sihanouk said he also hoped to meet with Secretary of State Cyrus Vance during his visit to the United States.

In Washington, State Department spokesman Hodding Carter said any request by Sihanouk to see Vance would be taken under consideration, but first a decision would have to be reached as to whether Sihanouk represented any government.

Sihanouk left the Cambodian capital only hours before the invading forces arrived, whisked from the site where he had been held under virtual house arrest by the Pol Pot government, whose case he is now pleading.

Sihanouk explained his support for the ousted Cambodian government on patriotic grounds, comparing it to Frenchmen who rallied to Gen. Charles De Gaulle after the German invasion in World War II.

"Cambodia can be compared to Poland, which was invaded and smashed in a very short time by Hitler's Germany army," he said. "This is not a civil war.

"Cambodia as a whole -- the people, the nation, the government -- we are victims of naked agression by Vietnam. Vietnam is colonizing our country," he said.

The provisional government of Heng Samrin has opposed Sihanouk's appearance at the United Nations, saying he and the Pol Pot government no longer represent Cambodia. The Soviet Union and its allies reportedly are lobbying behind the scenes to block a meeting.

The former Cambodian leader said he did not expect anything more from the United Nations than a moral condemnation of the Vietnamese.

He said, however, that this would put "diplomatic pressure on the Vietnamese" to leave Cambodia.

Sihanouk said Pol Pot and his close colleagues have set up a government outside Phnom Penh to conduct a campaign of guerrilla warfare. The new government in Phnom Penh is pressing its military drive against the Pol Pot forces with heavy Vietnamese support.

"The Vietnamese are hungry, they invaded to have our soil and our rice," Sihanouk said. "Maybe, if you say to them, 'You stay at home, we will give you rice and money,' maybe they will leave."

As for his own future, Sihanouk said he would eventually return to China to live, but wanted no role in Cambodian politics.

Sihanouk's current trip is his first outside Cambodia since 1976. After Sihanouk lent his international prestige to the Communists as figurehead of their government-in-exile, he was "retired" in 1976, unacceptable even as a nominal head of state to the radical regime.

Sihanouk, who retains respect among many Third World nations, was released as the Pol Pot government lost control of the country, in the apparent hope his international standing would make him a forcefull advocate of Cambodia's cause. In his news conference tonight, however, he made it clear his mission abroad would be carried out in his traditional independent style.