White, an American electronics designer who now lives in London, flew to Maputo, capital of Mozambique, last spring to visit a friend, an American working there for a French oil company. This report on White's misadventure in the former Portuguese colony, now governed by the one-time guerrillas of the Frelimo movement, is excerpted from the Sunday Telegraph of London.

IN NAZI GERMANY, the knocks came at midnight. In Marxist Mozambique, they come at high noon.

Three smiling plainclothes policemen flashed Frelimo badges, sauntered into the apartment and ordered me to sit. One, slight, with full beard, asked questions in faltering English. Why was I there? What was my occupation? Why did I, an American, live in England? Where did I get this Time magazine?

I could discern no pattern to his questions. The three examined every letter, every scrap of paper in my room, and everything on the floor except my address book, which one of them pocketed.

James [White's host] was due home for lunch, but arrived at 3, breathless. His refinery had been nationalized, and Romanians were to replace the French and English staff. He had been held all morning, and the government had taken his briefcase.

The three smiling men were waiti. They questioned him, went through his papers and kept his curriculum vitae, address book and a bill from his London real estate agent. They demanded to hear his cassette tapes and conducted a search of the bedrooms, bathroom and kitchen to the music of "Die Valkyrie."

Since nothing incriminating was found, we assumed we were due for an apology. Instead the men, still smiling, ordered us out of the building and into a white car marked ESTADO. They drove us to a white-and-lavender former storeroom on a side street, which was the Criminal Investigation Division (CID) headquarters. We were escorted into a large, dirty room and directed to sit on a dais in a picture window, where our further questioning attracted a crowd of passers-by.

Around us, male and female officials, wearing identical ill-fitting uniforms, shuffled papers and called each other camaranda as if engaged in som ecomical satire. But when they took our wallets and passports, it was more than clear they were not play-acting. Armed guards arrived and ordered us into a van. A short drive delivered us to the Maputo civil prison.

THE PRISONS yellow facade, even with peeling paint, looked like an impenetrable Kremlin wall. Doleful women, huddled on the pavement before the rusty green doors, were kicked aside as our guards marched us in. The bright sunlight abruptly ceased as the prison clanged chut.

We were led into a small, dim room, where a bored guard logged us in. We asked him if we could contact the American embassy. No. James' company? No. We were cut off from the world.

Dingy blankets were issued. A guard led us down a hall and left us in a big octagonal dome filled with other prisoners. Immediately, the resounding prison din ceased. The men rushed to surround and question us. "The knock came at high noon? Then you are political prisoners, too?"

The prison had four wings extending from the octagonal room, forming a cross. The wing through which we entered contained offices; the others had 16 cells, each containing four double-deck bunks. Aged cobwebs hung like black strings from the high, blackened ceilings. The remnants of screens in the barred windows rusted in shreds.

Of the 180 or so prisoners, 28 were Portuguese, eight Indian or Pakistani, and the rest blacks of various nationalities. We found empty bunks in Asia B, opposite the entrance, and shared Cell 2 with four blacks. They were brewing tea when we entered and asked us to join them. That was the first of the abundant kindnesses we were shown in prison. One of the men made up our bunks while we stood idly by, shakily, holding tin cups, dumbfounded by our surroundings.

Soon a young Pakistani came in and asked us to follow him to Cell 6, where we were introduced to Oliveras, a burly, hairy-chested, clean-shaven Portuguese of perhaps 30, wearing khaki shorts and sandals. He spoke in a low, unemotional tone. James speaks Portuguese, and relayed what he said.

"When you get over the shock of being here, you will find it not too bad. You will not eat the prison slop, of course: it's unfit for humans. Relatives and friends are allowed to bring our food. Until you are able to contact the outside, you will eat in Olivers' cell. You smoke? Here are cigarettes. Take this toothbrush. It's used but good. And this towel. There is a razor here and soap, which you may use at any time . . ."

We thanked Oliveras profusely. He never smiled.

At 4 p.m., food began to arrive in baskets, sacks, boxes and aluminum pails. The recipients' names were shouted repeatedly by the trusties - prisoners assigned special privileges because of their good conduct - adding to the already defeaning noise.

At mealtimes, most of the inmates formed groups and pooled their food. Oliveras had three sittings in his cell. He ladled out food like and Italian mama: After you said "Enough" there was always another spoonful.

At our first meal0, we heard some of the other prisoners' backgrounds. Some had owned small businesses or farms; two had owned taxis. The government had simply taken these from them and thrown the owners into prison.

Most had been transferred from Machava Prions, where they had been tortured. They held up swollen and scarred hands to show where knives had been inserted between tied fingers and twisted, so that the knuckles were cut and pried apart. Some had been thrown into chin-deep water in a squatting position and had weights piled on their heads. Others had their faces held over spikes while guards danced on their shoulders - all this to find if they owned more property, or if and where they might have money hidden. None had been charged with a crime, although some had been in prison for up to 21 months.

Oliveras' crime, he assumed, was that he had sold a house for profit. He had been held in prison for 18 months without being charged.

THE NEXT morning began with the sloshing sound of wet burlap bags being dragged down the halls, so as to clean them. Soon the doors to the octagonal room were unlocked, and the prison's reverberating uproar started again; every kind of sound the human voice can produce - except laughter.

On the morning of that second day, we requested, repeatedly, at Oliveras' suggestion, an interview with the prison superintendent. It was finally granted. Escorted into his office, we found him charming, the black equivalent of the impeccably mannered Germans who ran the concentration camps. No, he was not allowed to contact the American embassy, he said, but promised to notify the head of the refinery, a friend of James'. The superintendent probably suspected that we had already smuggled a note out, which was correct.

On the morning of the third day, we stood vigil by the front door until the 11 o'clock food parcels began arriving and the names were shouted out. At 1 p.m., we were eating in Oliveras' cell when a commotion occurred at the front door. Then James' name was bellowed. A picnic hamper had arrived that would have done Fortnum & Mason proud: it was white and covered with a pink tablecloth and contained all the things one would hope to find, plus malaria pills and toilet paper. We knew it was the work of the English wife of the refinery head.

We rushed the veritable banquet to Oliveras' cell, and a cheer went up from the diners - not for the food, but for the fact that our whereabouts were known.

That afternoon, a vice consul from the American embassy arrived, but he was not encouraging. Our morale received another blow the next day. Another vice consul came and strongly advised us to accpet prison life and adjust to it. It had taken 10 months to get the last American out of this jail, he said, and 18 months for the previous one.

Adjust we would, James promised to teach me French and I made plans to scrub down the cell and repair the window screen.

THAT AFTERNOON, pandemonium broke out when 15 Portuguese names were called. They already knew from outside contacts that they were in line for deportation. They rushed to their cells and donned two pairs of trousers and two shirts each, because they knew they could leave the country with only what they wore. They gave their toilet articles to friends and assembled in the octagonal room. There was much hand-shaking and back-slapping. An hour passed. Then two, then three. Tension mounted and the men dropped.

Only minutes before their plane was to leave, a guard arrived, and the 15 men were assembled at the front door within view of the rest of us standing in the octagonal room. Respectful applause sounded when each name was called and the man turned to wave before leaving through the big green door. There were no dry eyes as the last man waved and disappeared.

Next day, 21 black Mozambicans were sent to a "reeducation" (forced labor) camp and seven Portuguese arrived from Machava Prison, all with swollen, scarred hands. Around 10:30, James and I were having coffee in Oliveras' cell when a trusty quietly told us to get ready to leave. There was no applause as we were escorted through the big green door. Outside, the doleful women still sat and waited.

The smiling leader of the three plainclothesmen who had taken us from hte flat waited in a van. As he drove south, we fearfully watched the turn signal, for we knew that Machava Prison was to the right. At the crucial intersection, he slowed down and elaborately signalled right. His smile broadened as he turned left.

Our money and passports were returned to us: we were driven to the flat and told we had 48 hours to leave the country.

Our first steps were to the American embassy, where we were received by the deputy chief of mission, Johnnie Carson, who acknowledged our thanks with a smile. We told him we were anxious to leave Maputo immediately and, although the daily flight was fully booked, he secured seats for us.

Back in the flat we gathered all the food and toilet gear we had accumulated, and a vice consul, James Overly, agreed to deliver it to Oliveras. The embassy limousine took us to the airport, and Overly followed us every step through customs.

It is not uncommon for peopl, even after clearing customs and boarding the plane, to be called back by the Frelimo. Therefore, it was reassuring to see the vice consul standing in the terminal doorway until we cleared the runway. We landed in Johannesburg 45 minutes later.

At Jan Smuts Airport, we were surprised by a sound that we hardly ever heard in Mozambique laughter.