Zambia has begun providing armed escorts for traffic on the main highway from the capital to neighboring Malawi after a series of attacks on cars and trucks by groups of heavily armed youths.

Already, two persons traveling along the road -- a Zambian farmer and an Asian woman of British nationality -- have been killed in the past several weeks by what the local press has described as "armed bandits."

The Zambian Daily Mail reported today that the army had put up roadblocks 25 miles east of Lusaka and from there was escorting motorists in convoys along a 55-mile stretch of the highway.

It said the "gangsters" were members of the Rhodesian Army's elite Selous Scouts, a commando group used in attacks on nationalist guerrilla camps both here and in Mozambique. If this is ture, it would mean the Rhodesians are still operating deep inside Zambia since a series of air and ground raids on these camps began in late October.

The problem of maintaining law and order on such a principal Zabian artery reflects the continuing unsettled state of the country following the Rhodesian raids, the last of which came just before Christmas. No one is really certain whether the "bandits" are Selous Scouts or dissient nationalist guerrillas.

It is the prevailing view in Western diplomatic circles here and among some Zambian officials, however, that the bandits are deserters from the army of the Zimbabwe African People's Union. It is believed some nationalist guerrilas fled their camp near Rufunsa on the highway to Malwai when the Rhodesians attacked it last October and have remained out of control ever since.

A spokesman for the People's Union, whose headquarters is located here, heatedly denied this version and charged it was part of a "well-calculated campaign" against his group by the Western, - -particularly the British -- press, seeking to drive a wedge between the nationalists and Zambia.

He pointed out that similar accusations made last November against the People's Union for the killing of a white Canadian woman on a farm near another guerrilla camp had turned out to be false. The farm's manager was eventually charged with the murder.

Whatever the truth, the attacks on motorists seem to have begun shortly after the first Rhodesian raid on the Rufunsa camp in October and increased steadily ever since.

The attackers seem to be surprisingly well-armed and to have enough weapons to sell some to villagers along the highway. The Daily Mail today spoke of a "wave of terror" in the same area last month when it said bands of armed youths raped women, beat up motorists and attacked a Roman Catholic priest.