On the eve of the nonaligned summit in New Delhi, China has announced a five-point peace plan for Kampuchea. The move is expected to counter Soviet pressure to gain legitimacy for the Vietnamese-backed regime in Phnom Penh. It should also give support to Kampuchean resistance groups seeking recognition by the nonaligned nations.
Although portions of the plan have been mentioned before, Western diplomats here say this is the first time China has offered in detail a peace package that does not require the complete withdrawal of Vietnamese troops before starting the negotiating process.
China is believed to have included portions of the plan in the first round of Sino-Soviet consultations held in Peking last October. The second round has just begun in Moscow March 1, with Qian Qichen heading the Chinese delegation and Leonid Ilychev, the Soviet. Both diplomats hold the rank of vice-minister of foreign affairs.
At the New Delhi meeting China, although a bystander and not a participant, is backing the effort by the five members of the Association of Southeast Asian Nations (ASEAN) to get Prince Sihanouk's Democratic Kampuchean Coalition government seated. Vietnam, which is a conference participant, is trying with equal determination to win seating for its protege, the Heng Samrin regime. Vietnam has offered its own version of partial troop withdrawal from Kampuchea, which both China and ASEAN have rejected.
The five points of the Chinese plan are:
1. Vietnam must first declare an unconditional withdrawal of all its troops from Kampuchea.
2. The Soviet Union should cease supporting ''Vietnam's aggression against Kampuchea'' and urge Hanoi to ''withdraw all its troops.''
3. If the Vietnamese government should decide to announce a withdrawal of all its troops, the Chinese side would be willing ''after the withdrawal of the first batch of Vietnamese troops, to resume negotiations with Vietnam. . . .''
4. After the withdrawal of all Vietnamese troops, it should be up to the Kampuchean people themselves to settle all their internal issues. China ''wishes to see an independent, peaceful, neutral, and nonaligned Kampuchea.''
5. China is willing to make a joint commitment with other countries to refrain from interference in the internal affairs of Kampuchea, to respect its independence, neutrality, and nonaligned status and to respect the result of the Kampuchean people's choice made through a genuinely free election to be held under United Nations supervision.
The proposal was announced at a press briefing here March 1 given by Qi Huaiyuan, spokesman of the Chinese Ministry of Foreign Affairs. This will be the first of a series of weekly press briefings on various topics. Although so far questions are not permitted at these briefings, they constitute another step in the ministry's gradual though still limited accessibility to the foreign press since the installation of Wu Xueqian as minister last November.
Soviet sources here have said that China should talk directly with Hanoi about Kampuchea, rather than making this a topic of Sino-Soviet discussions. At the same time Moscow is understood to have assured Thailand that it would not permit Vietnamese troops to invade Thai territory in ''hot pursuit'' of Kampuchean guerrillas loyal to the Sihanouk coalition government. Hanoi, while expressing confidence about continued Soviet support, has given indications of concern about the possibility, however remote at present, of a Sino-Soviet rapprochement at Hanoi's expense.
These currents and cross-currents show the possibility of movement on the long-stalemated and tragic Kampuchean question. Western observers doubt, however , that the nonaligned summit in New Delhi or the current round of Sino-Soviet discussions will lead to concrete new developments. Vietnam does not seem about to yield on the question of stationing its troops in Kampuchea. Meanwhile the albatross for the Sihanouk-led coalition is that its militarily strongest component continues to be the Khmer Rouge, whose excesses partly precipitated the Vietnamese invasion in 1978.
Like China, the United States is a bystander at the New Delhi conference. Despite the coolness between the Reagan administration and Peking over Taiwan, Washington's long-term aims in Southeast Asia coincide with Peking's. The arrival in Washington as Chinese ambassador of one of China's most senior and experienced diplomats, Zhang Wenjing, could advance the search for common interests.