Pro-Communist newspapers here reported yesterday that Peking expects an exodus of up to 300,000 Chinese refugees from Vietnam. Hanoi, meanwhile, struck back at the Chinese with suggestions that they were soft on capitalism.

Hanoi repeated its call for negotiations to mend the breach between the former Communist allies. A diplomatic note proposed that a meeting begin a Peking within a week, Hanoi radio said.

On the other hand Vietnam's leading official newspaper also made its strongest attack on peking yet for allegedly helping "capitalists of Chinese origin" in Vietnam while ignoring atrocities against Chinese living in Cambodia.

Neither the Vietnamese nor the Chinese made any discernible move to stop one of the most sudden and disruptive flights of refugees in recent years. Thousands of ethnic Chinese continued to cross the border from Vietnam and Peking sought permission to send ships for thousands more.

Hanoi has called the exodus illegal but has shown little interest in halting it while it still has difficulty feeding its remaining population. Peking has so far not reponded publicly to calls for negotiations. Instead it continued yesterday to broadcast dramatic accounts of Vietnamese mistreating Chinese.

Both of Hong Kong's morning newspaper with links to Peking printed on their front pages yesterday a report from the Japanese Kyodo news agency tsat Chinese officials expected another 210,000 Chinese refugees to follow the 90,000 that have already entered China from Vietnam, most within the last two months. An estimated 1.4 million of Vietnam's 47 million people are ethnic Chinese.

One of the Hong Kong papers, the Ta Kung Pao, printed a statement from an unnamed Chinese official in the Kyodo report that Vietnam "would eat their bitter fruit" if they continued persecuting Chinese. The newspaper included that Japanese agency's speculation that "China would take some revenge." The newspaper had earlier printed reports of a massive cutoff of Chinese aid to Hanoi, still not officially confirmed by Peking.

Factors that might be expected to limit the conflict between the two nations, such as Peking's desire to keep Hanoi from depending too much on the Soviet Union and Hanoi's desire to continue to receive vital Chinese aid, have had little apparent effect so far on the escalating accusations.

In a commentary yesterday, Hanoi's Communist Party newspaper Nhan Dan referred to "the Chinese side's continuous propaganda to distort the truth." It said "nationalism, be it chauvinism of countries big or small, is a hangover from feudalism and capitalism which genuine Communists must condemn and refute."

"The Vietnamese people are not so stupid as to seek trouble from China," the newspaper said. It asked, "Why is it that the false reports spread by bad elements among the Hoa (Chinese) people aimed at coercing and fooling them into leaving en masse for China coincide with the (Cambodian) authorities' escalation of their large-scale aggressive war to the whole length of the Vietnamese border?"

The newspaper complained about Peking reports of deaths and injuries suffered by ethnic Chinese in southern Vietnam, where local Chinese have protested government takeovers of their small private shops and businesses.

Nhan Dan chided one of the pro-Peking newspapers here for calling in the "socialist transformation" campaign in Vietnam "a surprise attack to rob the Chinese residents of Cholon," the predominantly Chinese suburb of Ho Chi Minh City, formerly Saigon.

"One should ask," Nhan Dan said, "must the socialist transformation of private industry and commerce, a universal law of socialist revolution which has been applied in China, stop in socialist Vietnam (because of) of wealth of a number of capitalists of Chinese origin (and Vietnamese capitalists too!) even though this wealth was wrung from the sweat and tears of the Vietnamese working class and people including quite a few Vietnamese of CHinese descent."

The official Vietnam News Agency reported a meeting of more than 200 ethnic Chinese in Ho Chi Minh City who challgened Peking statements that Chinese had been ostracized and denied rations or means of livelihood.

One Chinese said he fled the harsh new Communist government of Cambodia, which Peking supports, while 10 other members of his family left behind were killed or died of exhaustion. He said Vietnam officials cared for him while Peking remained silent about "Cambodian atrocities."

China's official New China News Agency yesterday called Hanoi's suggestions that Peking had encouraged the mass exodus "shameless pretexts for discriminating against Chinese residents."

In a continuing series of interviews with refugees, the Chinese agency told of a man who had taken his family to China after authorities had closed a plasticware cooperative he was operating with other overseas Chinese in Haiphong. At a railroad station on his way to the border, he said Vietnam security officers began to rough him up.

"My two little daughters were frightened to tears at the sight of them kicking and beating me. To my horror, the Vietnamese security men actually threw them out of the train window. Both children suffered injuries," he said. He, his wife and daughters were interrogated for 10 hours and then sent on their way to China after all their belongings, including watches and eyeglasses, had been confiscated.

The Chinese agency reported that hundreds of people needed medicl care afte crossing the border, including one man who died from injuries suffered in a fall off a cliff.

The sudden Chinese exodus appears the result both of the harsh new economic measures taken against urban shopkeepers, who are traditionally Chinese, and of the fears and distrust engendered by Hanoi's war with Cambodia, a staunch ally of Peking.

Whatever the truth of charges that the Vietnamese began to cut rations for ethnic Chinese and draft them into the army, many ethnic Chinese must have realized how the war would hurt their relations with their Vietnamese neighbors and what trouble they could avoid by emigrating. Vietnam's general economic depression and food shortage encouraged the exodus.

The widespread reports of Vietnamese persecution that were spreading to Chinese communities around the world, and the sudden demands on China's limited refugees aid facilities, apparently forced Peking to bring the conflict into the open. Peking already distrusted the Vietnamese and their links to the Soviet Union, Chinese's arch-enemy. They also had to advertise their concern for the refugees to score propaganda points with overseas Chinese worldwide and show up their nationalist rivals on Taiwan.

There is no way to tell how bad relations will become between the Vietnamese and the powerful northern neighbors they had feared and mistrusted for centuries.