Vietnam has warned China that it is strengthening its military defenses as relations between the two Communist neighbors continue to worsen.

[China has sent two ships to Vietnam to evacuate ethnic Chinese there, the New China News Agency reported yesterday. In a dispatch from Peking Reuter said the NCNA report said the ships will be going to Haiphong and Ho Chi Minh City (formerly Saigon) "to bring home Chinese residents persecuted by Vietnamese authorities.]

Although diplomats in Peking and Hanoi see little chance of a full-scale military conflict between the two countries, sources here with contacts in Vietnam say the Vietnamese have made unusual defense preparations on their coastline and near the Chinese border. Analysts here say Vietnamese propaganda broadcasts have significantly dropped many of the conciliatory statements that in the past had held out hope for renewal of close Sino-Vietnamese ties.

The tiny buffer nation of Laos also appeared to have been drawn into the conflict. An earlier broadcast monitored here reported the completion of one of several highways that an estimated 18,000 Chinese troops have been constructing in the northern part of the country. The report said the workers on that road would now "leave for their country," which indicated to analysts here that Vietnam was pressuring Laos to clear out as many Chinese roadbuilders as possible.

Hanoi's radio report on its military preparations with broadcast in Mandarin Chinese on June 9. Western agencies monitoring the broadcast just made available a transcript here.

It said "army men and people in Vietnam are heightening their vigilance, actively engaging in production and preparing to fight to defend their fatherland. The military command in Binhtrithien Province recently ran four training class to train regimental and battalion cadres and district-level military cadres. In Hue municipality as well as in other districts and cities, many training classes have been held to train village-level military cadres and command cadres for self-defense units in various offices and enterprises."

Since they grudgingly agreed to let the Chinese evacuation ships come in the Vietnamese have continue to lambaste Peking for its "arrogant, high-handed attitude" in insisting on the evacuation without prior negotiation. Chinese Vice Premier Teng Hsiao-ping last week rejected again any chance for talks on the issue, and the New China News Agency and pro-Peking Hong Kong papers continued their assaults on Hanoi's policies yesterday.

One pro-Peking newspaper, Wen Wei Po, said China had captured two Vietnamese secret agents sent into South China to assassinate a Chinese refugee who had been a hero in the Vietnamese war against the United States.

More than 120,000 ethnic Chinese have reportedly already fled from Vietnam into southern China by land, after Vietnamese authorities began to pressure Chinese into accepting Vietnamese citizenship as Hanoi's war with the Chinese-backed Cambodians escalated.