Rhodesia today escalated its 4 1/2-year flight against black nationalist guerrillas by capturing a town 60 miles inside neighboring Mozambique and announcing that it would hold the town until all guerrillas have been cleared from the area.

Gen. Peter Walls, commander of the Rhodesian operation, said his troops would continue to operate inside Mozambique until "task is complete." he gave no indication of when this would be, but sources said the Rhodesians would probably withdraw by Thursday.

Of the three "hot-pursuit" strikes into Mozambique, Rhodesia has acknowledged in the past year, the current one appears to be the most serious setback for the insurgent forces fighting the white-minority government of prime Minister Ian Smith.

In addition to capturing the town, Mapai, the Rhodesian troops destroyed three guerrilla camps and killed 32 rebels, Walls said. Mapai was the main administration base for the guerrillas, according to Walls.

Rhodesian air support also disrupted insurgent, according supply lines, Walls said, adding that a "considerable amount" of arms, equipment and supplies used by the Soviet-backed forces of the Zimbabwe African National Union liberation movement was captured or destroyed. Rhodesian troops suffered only minor injuries, he said.

The strike, which began Sunday, was the result of Rhodesian intelligence reports that there was an insurgent buildup in Mozambique, according to Walls.

In addition to Mapai, the bases hit were at Rio, three miles inside Mozambique along the Limpopo River, and at Modulo Pan and St. Jorge do Limpopo, 40 and 50 miles from the border.

Walls admitted that casualty figures for rebels were much lower than on the previous two strikes, in August and November last year, when several hundred insurgents were reported killed. But he said he was not disappointed in the operation. Earlier reports indicated that 40 guerrillas had been killed.

The raid did not quiet the rebels entirely. While the Rhodesians were in Mozambique, insurgents staged a mortar attack on Vila Salazar, the Rhodesian border base from which Walls' troops were operating, according to a Rhodesian military communique tonight.

Walls emphasized that Rhodesia does not want to violate Mozambique territory except to strike at guerrilla bases and said he does not want to provoke Mozambique's troops, which could further complicate the Smith government's fight against the rebels.

The raids were announced as an Anglo-American "consulting team" continued to try to work out a new set of proposals to settle Rhodesia's 11-year-old constitutional crisis, and there was no immediate indication of what the raids' impact would be

Two members of the team left Salisbury today to meet in Maputo, Mozambique's capital, with Robert Mugabe, head of Zanu. They are to go on to Zambia to meet with Joshua Nkomo, head of a group of anti-Rhodesian guerrillas based in Zambia and Botswana.