Genocide is a word which should be always be used with care. Random atrocities, however horrible, certainly do not constitute genocide.

Genocide is carefully planned.

According to the United Nations, genocide comprises 'acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group'.

That is why the savage and deliberate massacre of more than one million Cambodians by the dictator Pol Pot in the Seventies was genocide.

The methodical killing of 7,000 Bosnian Muslims in Srebrenica in 1995 was genocide.

So was the horrific slaughter of several thousands of Yazidis in Iraq by Islamic State three years ago.

And, of course, the term applies to the Holocaust, when the Nazis eliminated six million Jews during World War II.

Rohingya refugee receive bananas from a Bangladeshi volunteer after crossing from Myanmar into Bangladesh. More than 600,000 Rohingya have arrived in Bangladesh since a military crackdown in Myanmar in August triggered an exodus

Today, on the bloodstained border between Myanmar (formerly known as Burma) and Bangladesh, the world is witnessing genocide again.

Shamefully, it is being presided over by Aung San Suu Kyi, the Oxford-educated leader of Myanmar who was awarded the Nobel Peace Prize in 1991 in recognition of her lifelong battle for freedom. Even more disturbing, world leaders are doing nothing to stop it.

Myanmar is a former British colony which got independence in 1948 and is the world's 40th largest nation, sharing borders with India, China, Bangladesh, Thailand and Laos.

In 1962, the country fell under the control of a brutal military dictatorship. It was toppled thanks to the huge courage of Suu Kyi, who led Myanmar to free elections two years ago.

During the past few days, I have spoken to numerous survivors of the savage — and brutally calculated — onslaught unleashed by Myanmar's largely Buddhist army on its minority Muslim population.

More than 600,000 Muslims from the country's Rohingya ethnic minority have fled for their lives across the border to Bangladesh in the past ten weeks.

Every day, thousands more arrive and each has a heartrending story to tell. These traumatised refugees describe how the Myanmar army burnt their homes.

They recount stories of an orgy of killing and rape and of mass graves. In a hideous twist, they also relate how their military persecutors were egged on by Buddhist monks, betraying their principles of not harming any living thing by savagely trying to wipe out their religious rivals.

Though the oppression of the Rohingya has gone on for two decades, the latest outburst of mass killing was sparked on August 25, when a terrorist group claiming to represent the Rohingya struck at Myanmar security posts.

A Rohingya refugee child is pictured carrying another as they cross from Myanmar into Bangladesh

True, these attacks took place, but were easily repulsed. They certainly do not justify attacking hundreds of thousands of defenceless Rohingya villagers over recent weeks.

As a journalist, I've reported from Darfur, where thousands of men, women and children were slaughtered in Western Sudan in 2003 in the civil war as rebels accused the government of oppressing black Africans in favour of Arabs.

I've witnessed the reign of terror of death squads in Iraq and, in 2010, I visited a Nigerian village where bodies lay rotting in wells or buried in shallow graves — a result of the terrifying religious hatred between Christians and Muslims.

But none of these compared with the widespread or systematic killing that is happening in Myanmar.

Shamefully, the genocide is being presided over by Aung San Suu Kyi (pictured), the Oxford-educated leader of Myanmar who was awarded the Nobel Peace Prize, writes Peter Oborne

It is no exaggeration to say that this is one of the most heinous crimes of the 21st century.

Critics say that the evidence appears overwhelming, that the Myanmar government is intent on the annihilation of the minority population of Rohingya Muslims.

They say this is part of a policy of ethnic cleansing which has also meant that the minority has been denied citizenship and was mostly forced to live in ghetto-like camps.

When Suu Kyi came to power in 2015 — having spent years behind bars and under house arrest for her defiance of the military regime — her country's Rohingya population was estimated at just over one million.

Today, there are probably 300,000 left — the rest are dead or have fled across the border, a perilous journey over mountains and through forests.

They are frequently forced to hide in ditches, water-tanks and paddy fields. If found, they are killed.

Survivors simply cannot understand why the world will not intervene and come to their rescue.

'Please help us,' one old man asked as the rain poured down on his temporary home. 'Please tell our story to the world.'

On my arrival at the Balukhali refugee camp a few miles from the Myanmar border, I was braced for horrific accounts. Yet what I heard was infinitely worse.

Survivors spoke of an atrocity at Tula Toli, a Rohingya village in western Myanmar.

Early in the morning on August 30, around 150 government soldiers and 100 Buddhist civilians appeared on foot in the north of the village.

Using rocket-launchers, the troops began setting houses on fire. Terrified villagers fled the flames.

Rohingya refugees line up to receive humanitarian aid in the Balukhali refugee camp near Cox's Bazar, Bangladesh

As they ran, soldiers began shooting with what witnesses say were semi-automatic rifles.

Tula Toli lies between jungle and a gushing river. As villagers attempted to run for the jungle, a line of Buddhist civilians from non-Muslim villages holding long swords blocked their path.

The only place to go was the riverbank. Soon, the entire village had gathered on a large sandbank on the river's edge. That was the signal for the real killing and savagery.

Abdullah, a village mullah, estimates fatalities at around 1,500 people, including his wife and five of his six children (one married daughter escaped unharmed as she was living in another village).

He and around 15 other what he calls 'stronger people' swam the river and hid in a cemetery. From there, 40 yards away, they watched the horrific scene unfold.

Abdullah says he witnessed soldiers separate the Rohingya into three groups: men, young women (including girls as young as five) and old women or, as Abdullah chillingly described them 'those who are not so beautiful'.

Some villagers lay down to try to prevent themselves being forced into groups. It was no use.

The soldiers opened fire. 'All the young men were shot at once,' recalls Abdullah. 'It took less than ten minutes.'

When the firing was over, the soldiers walked over to the pile of bodies to check for survivors. If they saw signs of life, they hacked them to death with a machete.

After a five-minute pause, in which they did not reload, the soldiers opened fire on the old women.

Every day, thousands more Rohingya refugees arrive and each has a heartrending story to tell, writes Peter Oborne

'They put blankets on the piles of dead bodies, then they poured on petrol and just lit a fire on the piles of the bodies,' Abdullah recalls. 'And while there was a big flame, they throw the small children — while still alive — onto the fire.'

Abdullah says he saw the commander of the military sitting silently observing his troops as they went about their butchery.

This suggested that the soldiers were acting under prior orders.

But what happened next, according to Abdullah, was even worse.

The soldiers took the defenceless young women — a total of about 100 — to the edge of the forest.

Then they dragged them in groups of five or six back to the village, forcing them into the houses not yet burnt.

Abdullah was too far away to spot his family, but he knew that his wife and daughters were in these groups.

There followed a period of three hours' silence.

Rohingya refugees wait at a temporary shelter after crossing the border from Myanmar to Bangladesh this week

Abdullah describes seeing the womenfolk put inside houses as a stream of soldiers went in and out.

He could not see what was happening inside, but it takes no imagination to guess. Rape.

At the end of the three hours, Abdullah says the houses were set on fire, with the young women inside.

He could hear them screaming. Just seven were able to run to safety, although they had been badly beaten and burnt.

Abdullah never saw his wife or daughters again.

The soldiers went down to the river and dug a large hole into which, with the help of non- Muslim villagers, they dumped the bodies.

Only a few very young children were still alive. Witnesses say that some, too, were then burnt alive, others thrown into the river.

At 4.30pm, Abdullah set off on the three-day walk across the border to Bangladesh where, ten days later, he met up with his married daughter.

I was unable to establish the truth of Abdullah's account by travelling to Tula Toli myself.

Rohingya refugees cross the Naf River at the Bangladesh-Myanmar border in Palong Khali, Bangladesh

This is because the Myanmar army won't allow foreign observers into areas where, euphemistically, they say 'clearances' are taking place.

However, other survivors, as well as independent international observers, have confirmed the basic facts of his terrible story.

Abdullah's testimony fits the wider pattern of atrocities which have taken place in Rohingya areas in the past ten weeks.

Other refugees told me how tens or hundreds have been killed in their villages during the state-sponsored terror.

Mohammed, a betel leaf seller, says soldiers attacked his village of Dar Gyi Zar and he witnessed 'more than 100 dead bodies'.

From his hiding place in the forest, he then saw soldiers gather up corpses and burn them. They then put the remains in bags and threw them into the river.

Again and again, I heard the same stories about the epidemic of killing and rape of the Rohingya.

The truth is something dark and terrible is taking place in Myanmar — and, disgracefully, world leaders are turning a blind eye.

Experts have been warning that a genocide is underway for some time. Two years ago Queen Mary's University in London issued a prophetic report, Countdown to Annihilation: Genocide in Myanmar, which explains that the persecution of the Rohingya Muslims should be seen as genocide and not as ethnic cleansing, or anything else

Matthew Smith, of the human rights group Fortify Rights, which has warned of an impending genocide for years, told me: 'The death-toll is horrific. It is much larger than anybody has estimated.'

He pointed out the Myanmar government had not allowed in outsiders to make a record of casualties: 'There's normally a reason for that. That's not a good sign.'

Chillingly, Mr Smith says: 'We may not have seen the worst of it. There is a distinct possibility we shall see more mass killing in the coming weeks.'

That is why the world must respond now. Britain — which ruled the country for more than 120 years from 1824 — has urged the UN Security Council to discuss reports of mass civilian deaths. Otherwise, London's response has been utterly pathetic.

The Left-wing British Establishment which has lionised Aung San Suu Kyi for years is also complicit with her silence.

However, her supporters point out — correctly — that the army is largely outside her control, and the true responsibility lies with Senior General Min Aung Hlaing, the commander-in-chief of Burma's armed forces.

Yet Suu Kyi must shoulder huge blame and is guilty of falsely claiming the 'clearances' ceased on September 5. She has also asserted that the brutal military response has been justified by attacks on Myanmar security command posts by Rohingya terrorists in August.

One reason for the feeble international response may be a fear of offending China, Myanmar's regional protector.

At the very least, targeted sanctions must be placed on the military chiefs. The UN must as an imperative send a fact-finding mission to Myanmar to establish the truth of what is happening.

Above all, Aung San Suu Kyi must be persuaded to speak out against the killings — and if she refuses, she should be stripped of her Nobel Peace Prize.

There is still enough time to stop Myanmar's remaining 300,000 Rohingya from meeting the same fate as the doomed villagers of Tula Toli.

Victims' names have been changed to protect identities.