The biracial Zimbabwe-Rhodesia government of Prime Minister Abel Muzorewa today acepted Britain's plan for a cease-fire in its war with Patriotic Front guerrillas.

But Patriotic front leaders Joshua Nkomo and Robert Mugabe boycotted today's session of the Rhodesian peace conference here because they did not want to be rushed into agreeing to the cease-fire plan.

It calls for their guerrilla forces, now dispersed in Zimbabwe-Rhodesia and neighboring nations, to assemble at up to 15 places in the country so that their compliance with the cease-fire can be monitored and they can be assured food, shelter and safety from attack.

Nkomo and other Patriotic Front leaders object to this, calling the proposed assembly sites "concentration camps" into which their troops would be "herded like cattle."

The Front leaders want to "regroup" their troops with the Salisbury government's throughout the country, but the British believe the cease-fire could not be monitored this way. Their plan provides for the Salisbury government forces to be monitored in their existing bases, just as Front guerrillas would be watched at the assembly points.

Spokesmen for the Salisbury delegation said today, however, that their positions would include bases in the field, which the Front believes would give the Salisbury forces the run of the country.

Zimbabwe-Rhodesia's Deputy Prime Minister Silas Mundawarara said at today's conference session his government was accepting the British plan, even though it was "highly unpalatable" for its military forces to submit to the authority of a British governor during the transition to legal independence under black-majority rule.

He said the Salisbury government would have preferred that the guerrilla forces be sent back to their bases in neighboring Zambia, Botswana and Mozambique. And he promised that Salisbury's attacks on those bases would continue as long as the guerrillas kept infiltrating into Zimbabwe-Rhodesia before a peace agreement is reached.

British spokesman Nicholas Fenn said he thought the Patriotic Front had misunderstood the British plan, which he said "does not imply surrender of humiliation" of the Front guerrillas "and emphatically does not mean they will have to surrender their arms."

Fenn added that he thought the Front's angry reaction last week to a British request that they formally reply to the cease-fire proposals today was an argument "on procedure" that could be resolved.

Nkomo and Mugabe met privately today with the conference chairman, British Foreign Secretary Lord Carrington, to tell him they would not attend today's session but wanted to negotiate further.

They will meet with Carrington and British officials again Tuesday to discuss their specific objections to the cease-fire proposals. Fenn noted that the Front leaders have not rejected the plan nor walked out of the conference.

If the Front agrees on the general outline of the British plan, the warring sides' military leaders will negotiate the number and location of guerrilla army assembly points and the bases at which Salisbury's forces will be located.

There is now little hope that a final peace agreement can be reached this week, in part because Carrington will be preoccupied by an important Common Market summit meeting in Dublin Thursday and Friday.

Fenn emphasized again today, however, the British view that if final agreement is not reached soon, "there is a danger that the achievements of the conference so far might slip out of our grasp."