In apparent response to sluggish Patriotic Front compliance with the Rhodesian cease-fire, the British governor, Lord Soames, today warned the guerrillas to report to designated camps by midnight Friday or be considered "unlawful."

Slightly more than 2,100 have gathered at the camps after four days of the one-week period allotted for the guerrillas to gather, a British source said. The number was "rising steadily but not fast enough," although he looked for a "very rapid" increase at the end of the period.

The source warned that the figures were midleading at this point because many guerrillas have entered camps and then left again ostensibly to bring back others. About 1,500 guerrillas are reportedly ready to enter camps.

Meanwhile, violence in the country increased despite the cease-fire which went into effect last Friday night.

Estimates of the number of guerrillas in the country range from 15,000 to a Front figure of 31,000 with the British leaning toward the lower figure. t

The British are not saying how many guerrillas reporting would be a sufficient number, but if many thousands refuse to do so it could put in jeopardy elections scheduled for late February to choose a black-majority government.

Britain says there is no question of extending the cease-fire or election dates.

Soames, Britain's temporary ruler of the colony, is authorized to use the police and Rhodesian security forces against any guerrillas who have not assembled as required by Friday midnight under the terms of the Dec. 21 Rhodesian settlement negotiated in London.

Any major military actions against the guerrillas, however, could unravel the entire agreement painstakingly negotiated by Britain over 15 weeks between the guerrillas and the white-supported Salisbury administration of Bishop Abel Muzorewa.

A key reason for the agreement was pressure applied to the guerrillas by its African supporters, who would have a hard time countenancing concerted military action against the Front carried out under British authority.

In his broadcast speech, Soames, who visited some of the camps today, told the guerrillas, "You must make your way to your nearest rendezvous point or assembly place by Jan. 4 at the latest." Those who do not, he said, "will be unlawful." To encourage them to do so, he pointed out that their senior commanders were already cooperating in the cease-fire.

The Rhodesian military reported more than 60 cases of violence between midday yesterday and today that caused 14 deaths. The worst incident occurred about 100 miles north of Salisbury where police said they killed eight guerrillas who attacked a farm.

The 1,300-member Commonwealth cease-fire monitoring force also suffered its first casualties caused by the hostilities. A monitoring force vehicle detonated a land mine, breaking the leg of a British soldier and causing facial injuries to a Patriotic Front liason officer.

Last week before the cease-fire took effect, three British soldiers were killed in a helicopter crash but the British say it was an accident.

In another development, a spokesman for Joshua Nkomo's wing of the Patriotic Front announced that Nkomo, who is based in Zambia, would return to Salisbury Sunday. It will be the first time the guerrilla leader, under a death threat from many whites for his organization's shooting down of two commercial airliners, has been in Rhodesia since 1976.