Renewed squabbling among the four warring factions in Cambodia could stymie plans for a peace conference in Paris next month intended to sign an agreement ending Cambodia's 12-year-old war, Asian and Western diplomats said this week.

A protracted delay, according to two experts on Cambodia, would increase the chances of a return to power by the radical communist Khmer Rouge, whose rule from 1975 to 1978 resulted in the deaths of more than one million people.

While the International Conference on Cambodia, meeting in Jakarta earlier this month, reported "significant progress" working out details of a proposed peace agreement, neither the Phnom Penh regime nor the opposition coalition was represented at the meeting.

Representatives of the five permanent members of the U.N. Security Council are meeting in Paris on Friday and Saturday to continue work, but an attempt by Thailand to convene a meeting of the Cambodian factions this week in Bangkok appears to have failed, according to a Bush administration official.

"In spite of the advances . . . on the diplomatic scene," Raoul M. Jennar, a consultant to humanitarian organizations working in Cambodia, said in a recent private report, "in the field nothing changes. The battles continue and . . . the worst may still be to come."

Jennar, a former foreign affairs adviser to the Belgian Senate who spent most of October in Cambodia, said that during the rainy season which just ended, Khmer Rouge forces consolidated their military position and may be able to win a military victory in the dry season. A copy of Jennar's report was obtained by The Washington Post.

But Cambodian scholar Stephen R. Heder, who spent three weeks there in August, saw a possible Khmer Rouge victory not through military action but through the collapse of the increasingly weak Phnom Penh regime.

Heder, who did his research while on leave from the human rights monitoring group Amnesty International, said in a recent speech at the Australian National University that ". . . in purely military terms, the Khmer Rouge threat is not great and has clearly been overrated by those who for quite understandable political and moral reasons find it useful to cry wolf in this regard."

Heder and Jennar agreed that Cambodian Prime Minister Hun Sen, a proponent of reform, has been losing out to communist hard-liners in his government as the country's economic situation worsens.

"The greatest threat {to the government} is not a purely military one," Heder said. "It is the possibility that . . . the political narrowness of the regime" and the economic and social crises in the country "will result in a deterioration of political morale and military will that would create a growing vacuum into which the Khmer Rouge will increasingly be able to move."

The military situation "seems fairly quiet of late," a Bush administration official said this week.

Indonesian Foreign Minister Ali Alatas, co-chairman with France of the conference on Cambodia, said after the Jakarta meeting that he still hoped an agreement could be hammered out by the end of the year.

The conference is developing specific proposals based on a broad agreement reached in August by the five permanent members of the U.N. Security Council. That agreement calls for U.N. administration of the country prior to national elections. Conference members include the five Security Council members, the six members of the Association of Southeast Asian Nations (ASEAN), Indonesia, Laos, Malaysia, Japan, Australia and Canada.

The key obstacle now, Alatas and French representative Claude Martin said after the talks, is that the Phnom Penh government and the three-faction resistance coalition cannot agree on who should lead a 12-member interim Cambodian Supreme National Council that would oversee the country until the U.N.-supervised elections.

The resistance coalition, nominally headed by former ruler Prince Norodom Sihanouk, insists Sihanouk be chairman. The Cambodian government agrees, but only if Hun Sen is vice chairman. The resistance, dominated by the Khmer Rouge, objects to that, saying such a move would give legitimacy to the government.

Sihanouk is reported to have agreed to Hun Sen as vice chairman, but there is no sign that the Khmer Rouge have changed their view.