Comparing China's Vietnamese invasion to the military thrusts of Nazi Germany in the 1930s, the Soviet Communist party newspaper Pravda warned today that "the conflagration may spread if Peking's aggression is not stopped."

In a 3,000-word article, the official daily protrayed China as historically expansionist and declared that Peking is preparing a protracted war with Vietnam to achieve these goals and not the limited border action described by the Chinese leadership.

[Chinese forces reportedly pushed deeper into Vietnam and Chinese Vice Premier Teng Hsiao-ping told U.S. reporters in Peking that if the Soviet Union should enter the war, "We are prepared against them." Details on Page A16.]

The article, ascribed to Igor Agexandrov, a pseudonym believed used only for authorship of authoritative Central Committee views, appeared to be striving for a broad theoretical justification for some action to stem not just the border war but what Moscow perceives as Peking's larger and more dangerous ambitions.

Alexandrov's article also contained what have become staples of offical Soviet government and media responses to the invasion since the start: that China, frustrated by losing Cambodia, fabricated the border war with U.S. complicity to strike at strategic Soviet interests in Asia. But the article's thrust, by reinforcing and amplifying the historic development and intent of China, seemed to suggest broader reasons for wanting to thwart Peking.

The article's wording strongly suggested that it is intended as much for consumption by party regulars within the Soviet Union as for the outside world. For these reasons, the account, headlined, "Peking's Aggression Must be Resolutely Rebuffed," took on significance in assessing Soviet intentions in aiding Vietnam.

So far, Moscow has consulted once officially with Hanoi in accordance with a military clause of a recent friendship treaty and stepped up arms shipments and intelligence-gathering since the Chinese invasion began Feb. 17. Without making any other known overt move toward playing a direct role, it has called on China to withdraw "before it is too late."

Alexandrov asserted in the article that the Soviet Union "will fulfill" its treaty obligations, which require consultations "toward removing" attackers of either country.

He repeated Soviet charges that "the ambivalent stand taken by the U.S. ruling circles has as a matter of fact contributed to Peking's openly taking the warpath."

"The decision to start the invasion was taken by the Chinese leaders right after Teng Hsiao-ping's return from the U.S. and Japan and with regard to his report on the outcome of his talks in Washington," Alexandrov asserted. Once Sino-American tensions over Taiwan eased as a result of normalization, Peking "hastily" shifted troops from there to the Vietnamese border for the invasion, he said.

Broadly portraying China's recent diplomatic achievements as part of its plan of anti-Soviet encirclement, he wrote: "Peking does not deny the connection between the choice of the time for the aggression, the conclusion of the Sino-Japanese treaty and normalization of U.S.-Sino relations."

He said China set up the Pol Pot regime in Cambodia, "a criminal clique of degenerates," and then "planned in detail the wholesale annihilation of the Kampuchean (Cambodian) people, which was merely the first stage of a camouflaged military-strategic operation."

This consisted of "further Chinese assimilation" -- meaning repopulating the country with Chinese -- to transform it into an "important bridgehead" for encircling Vietnam and "offering direct access to Malaysia, Thailand and Indonesia," he added.

Meanwhile, it was learned last night that "for reasons of a temporary nature" the Soviets this week have refused to grant permission to several Western military attaches to travel to Khabarovsk, a Soviet Far Eastern city on the Chinese border. Permission to travel to Khabarovsk normally is granted routinely.

Western sources here have said they have no knowledge of any change in Soviet troop dispositions along the heavily reinforced Chinese border and they refused to speculate on the reason for the travel denial.