At the entrance to government ministries and in front windows of many state and private businesses, a visitor to Maputo these days sees a bulletin board covered with photographs of employes and below each one a strange alphabet of initials and dates from colonial times.

These are Mozambique's comprometidos , men and women identified as former collaborators of the Portuguese colonial power, on display for all to see with information about the group they served with.

After years of indecision about how to deal with nationals of uncertain loyalty, the ruling Frelimo party seems to have finally taken inspiration from the Chinese revolution and come up with a similar approach relying on social pressure and self-criticism rather than prisons and sanctions.

It is a novel technique in Africa and if successful could lead to a more humance way of treating political opponents than throwing them intoprison as many African governments want to do.

At the end of every war, the problem of what to do with enemy collaborators inevitably arises. In Europe after World War II, many Nazi agents fell victim to instant mob justice or were tried and sentenced to long prison terms.

Here in Mozambique, where Frelimo naionalists fought a decade for independence against Portugal, there has been no instant justice or trials for former collaborators. The most notorious who did not Flee to Portugal or Rhodesia were thrown into "reeducation camps" after independence together with Frelimo dissidents and opponents, prostitutes and criminals.

But the treatment of the comprometidos was greatly complicated by uncertainty over who had actually helped the Potuguese and how serious the crimes were. Furthermore, if all those who collaborated in some way with the Portuguese were imprisoned today, the government would probably grind to a halt.

Hundreds, if not thousands, of white and black Mozambicans participated voluntarily or under the draft in special Portuguese Army commando units such as the GE (special groups) and GEP (special paratroop groups) or in the hated secret police known as the PIDE. But the Portuguese destroyed their records before leaving.

Since Mozambique's independence nearly four years ago, many of these old collaborators have joined opposition groups such as Free Africa and the National Resistance Movement, have become informers for whiteruled Rhodesida or South Africa or have indulged in private economic sabotage.

Many others, however, are law-abiding citizens eager to forget their past, be forgiven by their compatriots and be integrated into the new Mozambican society.

The perplexing issue for the party has been to discover which are which and to devise a policy for dealing with those still involved in subversive activities or susceptible to being recruited as enemy agents.

Local and national elections held in 1977 ad a campaign last year to enlist new Frelimo party members led to the discovery and public exposure of a startlingly large number of comprometidos , many of them disguised as Marxist zealots.

In one cashew nut factory in Maputo, the party with the help of the workers last summer uncovered a network of 12 former collavorators who were busy sabotaging machinery and in contact with an opposition leader in Portugal. Even one editor of the weekly magazine Tempo, which acts as the voice of the Mozambican revolution, turned out to have been a former collaborator.

The new approach in neutralizing and trying to rehabilitate these past and present enemies of Mozambique's Marxist revolution was spelled out by President Samora Machel in a speech in early November when he called on the public to keep an "organized and permanent vigilance" over them.

"Their own reintegration into society depends on our vigilance over them," he said. "That is why we say these individuals must be known by all, in the home and at work. Their names must be in public lists, their photographs must appear on billboards in every place of work."

Beginning in mid-December, this is just what has happened. Each government department, factory and many businesses have posted a list of exposed former collaborators along with their pictures and a summary of their activities in the Portuguese Army or secret police.

Then at workplace meeting, the former agents are obliged to tell their colleagues what they did and why. They then must listen to personal accounts from others who suffered at the hands of the Portuguese. In the United States today, the technique might well be dubbed "group therapy," but here it is regarded as revolutionary self-criticism and public confession.

Machel has ruled out anyone, being fired from his job or punished in any other way than remaining under public scrutiny for the next two years. The reason for this is apparently not altogther humanitarian.

"Many of these former collaborators are highly skilled people and we need them in their jobs now," said a Mozambican journalist explaining the practical side of the new approach.

Reports on the success or popularity of it vary widely. Most Mozambicans seem to agree it is far better than sending all suspected or exposed former collaborators to reedution camps.

But some feel the public humiliation of having one's picture and past on public display for two years is not always equal to the nature and seriousness of the crime.

"Many of them were just doing their military service or working as secretaries or clerks in PIDE," remarked one Mozambican familiar with a number of specific cases.

Whatever the possible excesses of the new approach, it still seems a far better way of dealing with former collaborators than sending them to prison or reeducation camps on uncertain evidence and a far faster way of reintegrating them into Mozambique's new society.