The iron gate swung open and we were prodded, shuffling in our leg-irons, into a darkened concrete yard. Above us was the sound of more than 2000 African prisoners crammed into cells, shouting, singing and beating their feet. As the leg-irons were unlocked and we were pushed up the stairs, the stench of Harare's central remand jail hit me for the first time.

A mixture of sweat, excrement and rotting sadza - a white, doughy stodge made from maize - made me gag, the reflex colliding with the fear that seemed to be rising from my bowels and spreading upwards through my chest.

Our feet were bare, our toes squelching on the cold, damp steps. Dressed in regulation green canvas prison shorts and shirts, filthy and reeking of body odour, we had been assigned to category D for Delta (B) - murderers, armed robbers, rapists, kidnappers, sodomites and political "offenders" such me and my colleague Julian Simmonds from The Sunday Telegraph in London.

There were more than a dozen prison officers surrounding us, cackling and cracking jokes about the two white men they were about to lock up. We reached the dank corridor outside Cell B1 on the first floor, the cacophony from its occupants almost drowning out the jibes of the officers. The senior one pulled out a bunch of keys from the belt beneath his paunch and opened the door. "Meet the guys," he announced. Prisoners surged towards us and the door slammed shut.

I felt hands all over me, grabbing my arms, patting my back, even touching my hair. Some cried their names, others demanded cigarettes as we moved involuntarily towards the far end of the cell, some 23 metres long and 7.6 metres wide. "Welcome to Zimbabwe," one prisoner shouted in my ear. "Welcome to hell on earth."

The evening rollcall had just confirmed there were 105 inmates present in a cell designed to hold 25. Colin, a tautly muscular young man with "China Black" tattooed clumsily on his chest, came forward as we slumped on the concrete floor to tell us he was the prisoner "commanding" the cell. There was not much room, he said, telling us we had two blankets each to sleep in.

We lay down, our arms touching each other and the prisoners either side. This was where we were to rest, the lights on constantly and our every movement keenly watched. I looked up at the wall above me: 2.5-centimetre cockroaches were scuttling along it. The blanket I clasped was infested with lice.

The youth who was stretched out to my right spoke out. "I'm in here on six counts of armed robbery. I've been here for 21 months without trial. Can you help me? I want to go to London."

I turned to Julian and for a minute we looked at each other, neither daring to speak. For four days in a police cell, we had supported each other, sometimes laughing out loud at the situation we had found ourselves in. Already, we had formed a deep bond. "It could be worse," we had said. We were not being buggered or beaten. We would soon be released. Hot baths and cold beers awaited us. Now, however, there seemed nothing positive to say.

"We can survive this," I began uncertainly. "We may be here for a week, a month, or a year, but one day it will be over. We are both strong and one day we shall be free."

Three hours earlier, we had been bundled out of court in the rural town of Norton, 48 kilometres outside Zimbabwe's capital, and loaded into a battered green Bedford prison bus. As we drove north to Harare, a young prison officer - one of the "Green Bomber" recruits from youth militia and indoctrination camps - had recorded our details. I was now Prisoner 3190/05, he informed me.

"What is your tribe?" he asked us. "Who is your headman?" Julian and I conferred. Our tribe was English, we decided, and our headman and tribal chief was the Queen of England.

The reality of what was happening had still not hit us. We had just faced two charges in the Norton court: overstaying our visas and "practising journalism without accreditation" under Zimbabwe's notorious Access to Information and Protection of Privacy Act. Although we had been awarded bail by the Norton magistrate, the state prosecutor had invoked section 122, a clause that meant Robert Mugabe's Government could appeal against the decision. We had to be held in jail for seven working days while papers were filed.

We were allowed soap, a small towel and a toothbrush and were to address the guards as "Mambo" - Shona for "king", said the officer in charge. Any reading material we wanted had first to be examined by the prison censor, and we were forbidden a pen or paper. "You are in here for committing journalism," he said. "If you have a pen, you might commit journalism again."

We were there - officially - as tourists, nothing more. But we both felt that this tourist status permitted us to take a lively interest in all things Zimbabwean. We would gaze at Victoria Falls and enjoy the sights of Matobo National Park. But since our visit coincided with Zimbabwe's parliamentary elections, we would also take a good look at the queues outside the polling stations.

On election day, March 31, we headed south of Harare to the constituency of Manyame, where Hilda Mafudze, of the opposition Movement for Democratic Change, was being challenged by the Zanu-PF's Patrick Zhuwao, Mugabe's nephew. Our presence was glaring and, to Zanu-PF, unwelcome. "Go back to Tony Blair," one youth spat at me when I asked what the election meant to him. "What are your kind doing here?" he asked, pointing to the pale skin on my forearm.

At Chiedza Primary School polling station in Norton, things started to go wrong. Max Makowe, a local Zanu-PF apparatchik, seized his chance to strike a blow for Mugabe. "You are intimidating voters and interfering with the election," he shouted. He was joined by another Zanu-PF loyalist, and a young female constable was beckoned over.

We protested that we had done nothing wrong and attempted to leave. But Makowe barked an order to the policewoman and in an instant, a pair of handcuffs clicked shut around Julian's wrists. It was clear this was not something we could talk our way out of. Within an hour we were in Norton police station being interrogated.

That night we were marched off to the Norton police cell where we were to remain for four days, sleeping on urine-soaked blankets and unable to exercise, wash, or read. That cell, however, was nothing compared with the horrors of prison.

Our survival depended on items such as cigarettes and toothpaste, brought to us by supporters in Harare. These were traded for protection, provided by Henry, on remand for armed robbery, and Moses, charged with murdering a white couple he had worked for. They stood guard as we took cold communal showers and crouched over the latrines.

On the eighth day, I was ordered to report to a prison officer by the usual hiss and a click of the fingers. I was handcuffed and led into the outer courtyard, where a senior officer sat nonchalantly on a bench. I was ordered to sit at his feet while he lectured me about Zimbabwe. "There is no violence here," he said. "Zimbabwe is a democracy and people live freely here."

On the ninth day we were granted bail again, but we were taken back to the jail and told that "procedures" dictated we remain there. The next day, April 15, it was over.

As we walked out of prison, I whispered to myself the words I had learnt in Shona. "Ndakasununguka," I said, as Julian and I hugged each other in relief. "I am free."

The Telegraph, London