They are top-secret works in progress. It would be imprudent to discuss them with rivals, and tasteless to admit their existence in polite company. But one day they will be activated – the only question is when.

These are the "M-plans", the euphemism for scenarios drawn up by media organisations preparing to report the future death of Nelson Mandela.

The sensitivity around this taboo subject was underlined on Thursday when it emerged that for years international news agencies have been pointing hidden cameras at the frail 93-year-old's village home.

Under the front-page headline: "Madiba spied on", the Times of South Africa said the Associated Press and Reuters had installed at least three CCTV cameras at a house opposite Mandela's in Qunu, Eastern Cape province. Other reports quoted police saying this had been done without his family's knowledge.

The owner of the house, Chieftainess Nokwanele Balizulu, reportedly granted the agencies permission to install the cameras but would not admit whether she had received payment. A special police taskforce descended on Mandela's home to investigate the security breach, and the last camera was due to be removed on Thursday morning, the Times said.

South African police said AP and Reuters had broken the law and could "definitely" face criminal prosecution over the cameras. Vish Naidoo, a police spokesman, said: "All the homes of former presidents have been declared national key points. No person can film or photograph a national key point. We are investigating and will then hand the evidence to the National Prosecuting Authority."

Naidoo could not confirm whether the cameras were filming at the time of their discovery.

The article sparked an angry reaction on Twitter with South Africans accusing the media of ghoulish behaviour. Monde Sussmann tweeted: "The press are vultures installing cameras in Qunu waiting for Tata Mandela's eventual passing."

But Paul Colford, an AP spokesman, said: "They are not surveillance cameras. Along with other media, the AP has preparedness around Mr Mandela's eventual passing. The AP cameras were not switched on and would only be used in the event of a major news story involving the former president.

"We had similar preparedness outside the Vatican ahead of Pope John Paul II's passing."

The episode illustrated a culture clash between strongly held views of decorum around death and what can appear the cold pragmatism of competitive media bracing for the inevitable.

"The journalist in me thinks it's sensible planning but the citizen in me completely gets the natural anxiety about losing this man," said Ferial Haffajee, the editor of South Africa's City Press newspaper. "There are mores in African culture: we don't talk about someone's death, we don't plan for it and we certainly don't bring in lots of cameras."

Mandela is long retired from politics and was last seen in public nearly 18 months ago. When it comes, his death will shock South Africa, where he is revered like pope, monarch and statesman combined.

Heidi Holland, an author and columnist, said: "Nelson Mandela is a father figure so the fact he is going to die is very painful. It's like watching one's grandfather fade away. He represents integrity and a lot of things we are not entirely sure we will have in abundance without him.

"So to talk about his death appears unseemly. There is a form of denial about it."

But it is little secret that many journalists in South Africa occupy a curious limbo, gathering material, writing supplements and plotting logistics for the headline news that dare not speak its name. Major broadcasters have spent years – "and fortunes" – building studios, buying prime locations, pre-booking hotels and transport, hiring local "fixers" and signing up pundits.

Phillip de Wet, a freelance journalist and former deputy editor of South Africa's Daily Maverick, said: "I've never seen anything like it, a single news event where money is no object. Some of the things we've heard are quite extraordinary‚ competitive bidding for local fixers and block-booking every helicopter in the vicinity to stop others getting the helicopter shot."

Media groups often co-operate with each other, but not this time, he added. "It is considered a huge competitive event. They believe careers will be made and broken in those few days. Media organisations are playing their cards very close to their chests and there is a lot of secrecy.

"On top of that, it is a kind of taboo. The general public will see us as vultures if they see everything going on and the jockeying for position."

There was a foretaste of the mistrust earlier this year when Mandela was taken to hospital with a lung infection. The health scare ran wild on Twitter but journalists were frustrated by officials who called their thirst for information prurient and "un-African."

Mandela's mortality remains strictly off limits. Last year an artist caused an outcry by portraying him as a corpse in a parody of a Rembrandt work.

Justice Malala, a political commentator, said: "Culturally, black South Africans are very deferential on the subject of death. It's always, 'We don't talk about it.' We think we're softening the blow. The possible imminent passing away of someone in the village is always couched in euphemisms.

"But politically, it's baffling that we're not saying he's an icon, let's give him the honour and the funeral he deserves when he passes on. It surprises me the government is not saying publicly: 'We are prepared, there is a team.' It's the right thing to do. When someone of Nelson Mandela's stature dies, the country is going to come to a standstill. You have to be prepared for that."

The South African government has an M-plan of its own but this is rumoured to have been shared with only a handful of broadcasters. When the Guardian recently broached the subject with spokesman Jimmy Manyi, he looked down, shifted uncomfortably in his chair and said little.

A Johannesburg-based international TV journalist, who did not wish to be named, said: "The media sometimes ask government officials about it and they are told it is a taboo subject and an insensitive question to ask. Journalists will normally respect that but they also have a responsibility to produce coverage that will do justice to the stature and gravitas of Nelson Mandela."

But Donald Mothoa, a lifelong ANC member, finds the long build-up offensive. "Culturally, it's wrong," he said. "We don't do that. We wait for a person to die, then we start the preparations. You are pushing him to the grave."