Sitting on the Dnipro River in Russian-occupied Ukraine is Europe’s largest nuclear power station – on the frontline of a worsening war.

Over a period of a few weeks we spoke to two workers at the Zaporizhzhia plant.

And the warnings they gave of what could happen should send a cold chill around the world.

The interviews were conducted on the condition of anonymity and at great personal risk to them. They told us that if they were caught, they could be tortured, imprisoned, or worse. They know the dangers but still wanted to be heard.

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Neither of the technicians knew that we were talking to the other. But their testimony of the possibility of a major nuclear catastrophe was worryingly familiar. One of the men, who we will call Serhii, warned the consequences could cause devastation across much of Europe, Russia and the Mediterranean.

“The level of radioactive pollution, and most importantly the area of contamination, will be thousands of square kilometres of land and sea… it would be much, much worse than Fukushima and worse than Chernobyl.”

While some nuclear experts think that such an eventuality is unlikely, others have told us it’s a possible worst case scenario.

The Zaporizhzhia nuclear plant was captured by Russian forces in March last year at the beginning of Moscow’s invasion of Ukraine. Since then there have been major concerns about safety at the plant. Not least of all because heavy weapons, including shells and rockets, have hit the buildings.

Both sides blame each other. But our sources told us that Russia has been deliberately targeting power lines to disrupt the flow of electricity to Ukraine. These lines are essential for plant safety and the cooling mechanism of the reactors.

For 30 years, workers at Europe’s largest nuclear power station couldn’t imagine that there could be a power outage.

Since Russian forces occupied the site last year it has happened seven times.

The back-up generators we were told are also not being properly maintained, the other man, Mykola, told us that this was because of staff shortages.

He says that before the war there were 11,000 staff at the plant and now there may be as few as 3,500.

“There is the same deficit of workers for repairs who can actually do the servicing and fix problems. The quality of the workers is lower because the qualified staff left. So generally the situation here is deteriorating.”

Five of the six reactors are now in cold shutdown, but there are fears Russia may use the power plant to stage a false flag attack.

Ukraine’s defence ministry alleges Moscow could be about to simulate a major accident, such as a radioactive leak, as a way of stopping any Ukrainian counteroffensive in the south of the country.

Ukraine is expected to order its troops to reclaim territory lost at the beginning of the war in the coming weeks.

The power station has been under occupation now for 15 months and the technicians have told us that in the last few weeks the level of military activity has increased dramatically.

They’ve witnessed Russian forces, moving more armour, more ammunition and more guns into place as they fortify their positions.

Serhii says that he thinks it’s because they know the nuclear plant is safe from Ukrainian strikes.

“Ukrainian armed forces will not shell the station. That’s why they are multiplying the numbers of troops and vehicles here because if they did it in another place they would definitely get shelled by the armed forces of Ukraine.

“The thing is, one month and half ago there were two times less troops on the power station and now there are two times more which means they are definitely preparing for the counteroffensive.”

It is hard to know what is exactly going on inside, but we understand technicians are routinely intimidated to keep them silent – effectively held as hostages.

Mykola told us it’s a frightening place to work, but he has no choice.

“Everyone has their own story. And I think the most important thing is not to get into their hands because it’s unlikely you will get out and still be the human you were when you went in.”

The International Atomic Energy Agency is carrying out inspections, but it continues to express grave concerns about the nuclear plant and is calling for the area to be demilitarised immediately.

But there is no sign that will happen. In fact, it’s quite the opposite.