IT'S been described as "a hidden monstrous campaign" - but Brits don't understand what's going on.

An estimated 200,000 people have been detained in the Syrian regime, but it has been revealed that the UK public believes it's ISIS who is behind the mass torture and imprisonment.

6 Syrian President Bashar al-Assad ordered dissent against his government to be crushed in 2011 Credit: AFP - Getty

According to a survey conducted by Survation for the Families for Freedom Syria campaign, more than half said they had not even heard of mass detention and torture in the war-riddled country.

The campaign found that 40 per cent of the more than 2,000 people surveyed believed ISIS and other extremist groups were responsible for the most deaths since the Syrian conflict.

About 34 per cent believed it was Syrian government forces.

But peaceful campaigners are now working to raise awareness for the suffering in the country.

6 Smoke billows in the rebel-held town near Damascus following air strikes by Syrian government forces Credit: AFP or licensors

6 The little boy became a symbol of the horrors of the Syrian civil war Credit: Getty Images

Today, Big Ben missed more than 200,000 chimes after it was silenced for repairs - the same number of people estimated to be detained by the regime of President Bashar al-Assad.

The dictator has tortured and hanged more than 13,000 political prisoners in four years, according to campaign group Amnesty International. Many others died from starvation and disease in the barbaric Sedenya military jail.

In fact Assad is thought to be responsible for the vast majority of the estimated 500,000 dead and missing in the brutal six-year civil war.

The former captain of the Syrian national football team is among those feared to have been tortured to death after he vanished in Homs three years ago.

6 The campaigners sang outside Big Ben when it should have chimed Credit: Kevin Dunnett

6 Peaceful protesters flocked outside Parliament House to raise awareness of those detained in Syria Credit: Kevin Dunnett

6 The campaign is led by women, bravely sharing their stories Credit: Kevin Dunnett

A Syria campaign spokesperson said: "It's striking to us that whilst the numbers being detained and tortured by ISIS are much, much fewer than those facing this treatment by the regime, the perception is to the contrary."

In 2014, gruesome photos smuggled out on memory sticks showed the corpses of 11,000 prisoners electrocuted and strangled by Assad's henchmen.

War crimes prosecutors said it proved "industrial scale killing" by the regime.

Amnesty said at least once a week for four years, 50 at a time were given two-minute trials before being blindfolded, beaten and hanged in the basement.

Guards also forced prisoners to rape other inmates as part of widespread torture in the jail where an average of ten died each day, the human rights group alleged.

Amnesty said: “Saydnaya Military Prison is where the Syrian state quietly slaughters its own people.

“The victims are overwhelmingly ordinary civilians who are thought to oppose the government.

“Since 2011, thousands of people have been executed in mass hangings, carried out at night and in the utmost secrecy.”

The total number of men women and children held prisoner or forcibly "disappeared" by Assad's thugs and armed opposition groups over the past six years is around 200,000, according to the Syrian Network for Human Rights.

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