A blindfolded Robert Tait could only listen as fellow captives were given electric shocks and beaten by Mubarak's security services

The sickening, rapid click-click-clicking of the electric shock device sounded like an angry rattlesnake as it passed within inches of my face. Then came a scream of agony, followed by a pitiful whimpering from the handcuffed, blindfolded victim as the force of the shock propelled him across the floor.

A hail of vicious punches and kicks rained down on the prone bodies next to me, creating loud thumps. The torturers screamed abuse all around me. Only later were their chilling words translated to me by an Arabic-speaking colleague: "In this hotel, there are only two items on the menu for those who don't behave – electrocution and rape."

Cuffed and blindfolded, like my fellow detainees, I lay transfixed. My palms sweated and my heart raced. I felt myself shaking. Would it be my turn next? Or would my outsider status, conferred by holding a British passport, save me? I suspected – hoped – that it would be the latter and, thankfully, it was. But I could never be sure.

I had "disappeared", along with countless Egyptians, inside the bowels of the Mukhabarat, President Hosni Mubarak's vast security-intelligence apparatus and an organisation headed, until recently, by his vice-president and former intelligence chief, Omar Suleiman, the man trusted to negotiate an "orderly transition" to democratic rule.

Judging by what I witnessed, that seems a forlorn hope.

I had often wondered, reading accounts of political prisoners detained and tortured in places such as junta-run Argentina of the 1970s, what it would be like to be totally at the mercy of, and dependent on, your jailer for everything – food, water, the toilet. I never dreamed I would find out. Yet here I was, cooped up in a tiny room with a group of Egyptian detainees who were being mercilessly brutalised.

I had been handed over to the security services after being stopped at a police checkpoint near central Cairo last Friday. I had flown there, along with an Iraqi-born British colleague, Abdelilah Nuaimi, to cover Egypt's unfolding crisis for RFE/RL, an American radio station based in Prague.

We knew beforehand that foreign journalists had been targeted by security services as they scrambled to contain a revolt against Mubarak's regime, so our incarceration was not unique.

Yet it was different. My experience, while highly personal, wasn't really about me or the foreign media. It was about gaining an insight – if that is possible behind a blindfold – into the inner workings of the Mubarak regime. It told me all I needed to know about why it had become hated, feared and loathed by the mass of ordinary Egyptians.

We had been stopped en route to Tahrir Square, scene of the ongoing mass demonstrations, little more than half an hour after leaving Cairo airport.

Uniformed and plainclothes police swarmed around our car and demanded our passports and to see inside my bag. A satellite phone was found and one of the men got in our car and ordered our driver to follow a vehicle in front, which led us to a nearby police station.

There, an officer subjected our fixer, Ahmed, to intense questioning: did he know any Palestinians? Were they members of Hamas? Then we were ordered to move again, and eventually drove to a vast, unmarked complex next to a telecommunications building.

That's when Ahmed sensed real danger. "I hope I don't get beaten up," he said. He had good reason to worry.

We were ordered out and blindfolded before being herded into another vehicle and driven a few hundred yards. Then we were pushed into what seemed like an open-air courtyard and handcuffed. I heard the rapid-fire clicking of the electric rattlesnake – I knew instantly what it was – and then Ahmed screaming in pain. A cold sweat washed over me and I thought I might faint or vomit. "I'm going to be tortured," I thought.

But I wasn't. "Mr Robert, what is wrong," I was asked, before being told, with incongruous kindness, to sit down. I sensed then that I would avoid the worst. But I didn't expect to gain such intimate knowledge of what that meant.

After being interrogated and held in one room for hours, I was frogmarched after nightfall to another room, upstairs, along with other prisoners. We believe our captors were members of the internal security service.

That's when the violence – and the terror – really began.

At first, I attached no meaning to the dull slapping sounds. But comprehension dawned as, amid loud shouting, I heard the electric shock rods being ratcheted up. My colleague, Abdelilah – kept in a neighbouring room – later told me what the torturers said next.

"Get the electric shocks ready. This lot are to be made to really suffer," a guard said as a new batch of prisoners were brought in.

"Why did you do this to your country?" a jailer screamed as he tormented his victim. "You are not to speak in here, do you understand?" one prisoner was told. He did not reply. Thump. "Do you understand?" Still no answer. More thumps. "Do you understand?" Prisoner: "Yes, I understand." Torturer: "I told you not to speak in here," followed by a cascade of thumps, kicks, and electric shocks.

Exhausted, the prisoners fell asleep and snored loudly, provoking another round of furious assaults. "You're committing a sin," a stricken detainee said in a weak, pitiful voice.

Craving to see my fellow inmates, I discreetly adjusted my blindfold. I briefly saw three young men – two of them looked like Islamists, with bushy beards – with their hands cuffed behind their backs (mine were cuffed to the front), before my captors spotted what I had done and tightened my blindfold.

The brutality continued until, suddenly, I was ordered to stand and pushed towards a room, where I was told I was being taken to the airport. I received my possessions and looked at my watch. It was 5pm. I had been in captivity for 28 hours.

The ordeal was almost over – save for another 16 hours waiting at an airport deportation facility. It had been nightmarish but it was nothing to what my Egyptian fellow-captives had endured.

Later, I learned that Ahmed, the fixer, had been released at the same time as Abdelilah and me. He told friends we had been "treated very well" but that he had bruises "from sleeping on the floor". I had flown to Cairo to find out what was ailing so many Egyptians. I did not expect to learn the answer so graphically.

Robert Tait is a senior correspondent with RFE/RL. He was formerly the Guardian's correspondent in Tehran and Istanbul

• This article was amended on 10 February 2011 to remove references to electrocution (killing by electric shock). These have been corrected to 'electric shock'.