Numbers of dead and wounded and signs of physical destruction are usually taken as a measure of the violence and breakdown of order in any civil war. But, in practice, kidnapping can carry a greater charge of fear for a community. People are more terrified by an ever-present risk that they, their children or other relatives may be kidnapped than they are by a more momentary fear of being hit by a shell, a bomb or a bullet.

Kidnappings in Syria contribute far more to the atmosphere of insecurity and instability than is generally appreciated by non-Syrians. They are crimes that take place in the shadows, as both perpetrators and victims have an interest in keeping them secret.

Over the past year, they have become big business and everybody is vulnerable, particularly families with money since most abductions are carried out by criminal gangs working for profit. This is not the only motive – many kidnappings are tit-for-tat actions between hostile communities, either as a form of vengeance or to enable an exchange of hostages for a person held by the other side. Along the Syrian Lebanese border, Shia and Alawites have been seized to get a relative freed from a Syrian government prison. The distinction between commercial and political kidnappings is not definitive, as gangsters pretend to act on behalf of their community or in opposition to the government.

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Sometimes the identity and motive of the kidnappers is frighteningly obscure, and it never becomes clear if people are being held for ransom or are already dead. What happened, for instance, to two eminent Christian clerics from Aleppo, the Greek Orthodox Bishop Boulos Yazigi and his Syriac Orthodox counterpart Yohanna Ibrahim, who went on a mission of mercy on 22 April this year into rebel-controlled territory to try to free two kidnapped priests? They were themselves abducted by a jihadi gang, which was reportedly led by Chechens, and nothing has been heard from them since, leading to fears they were murdered.

You do not have to go far in Syria or among well-off Syrians abroad to find stories of relatives kidnapped and bought back or still being held prisoner. Earlier this summer in Damascus, the Syrian deputy foreign minister, Faisal Mekdad, who comes from near Daraa in the south, told me that his 84-year-old father had been kidnapped in May and held for 14 days. His nephew had similarly been abducted and mistreated. Two senior Syrian army officers asked me not to mention their names for fear that family members might be kidnapped or killed. The situation in Syria is now getting as bad as Iraq after 2003, when I did not know a single well-off Iraqi family that had not had a close relative grabbed by gunmen and held for ransom.

Kidnappings take place largely though not exclusively in rebel areas and they are on the increase. Peter Bouckaert, the Geneva-based emergencies director of Human Rights Watch, confirms this in an interview with the website Syria Deeply: "The kidnappings have been going on for about a year," he said. "It's really intensified. It started mostly when fighting broke out in Aleppo, and has developed and grown since then into a broader trend across many parts of Syria, and is also spilling into neighbouring countries."

Kidnap gangs are becoming better organised and have good intelligence about when and where their victims will be easy to snatch. Mr Bouckaert cites the recent case of a prominent member of the Armenian community in Aleppo, who was travelling to Beirut by bus when it was stopped by gunmen who asked for him by name and took him away, knowing that the Armenian community in Damascus would pay to get him back. Again, there is an ominous parallel with Iraq, where gangs would pay informants a cut of the ransom for identifying a vulnerable and lucrative target. To this day, people selling houses in Baghdad do so without publicity because neither the seller nor the buyer wants it known that a large sum of money is about to change hands. Wealthy doctors used to be favourite targets, as kidnappers could gain easy access to them by pretending to be in need of medical attention.

Kidnappings spur flight and demoralise those who stay behind. They also have a long-term political impact. They have done much to discredit the Syrian opposition because it is in rebel-held areas that most people are seized and held (though there are stories of people being taken in government-controlled areas, too). US Senator John McCain, a militant advocate of Western help for the rebels who slipped into Syria to be photographed with rebel leaders, was embarrassed when one of them was alleged to be the kidnapper of 11 Lebanese Shia pilgrims. Two Turkish pilots were abducted from a bus outside Beirut airport last week to put pressure on Turkey to use its influence to get the pilgrims released.

The criminalisation of the opposition in Syria is following the same pattern as in Chechnya after 1999 and in Iraq after 2003. In all three cases, heroic militiamen who may have begun as defenders of their community became indistinguishable from bandits. Their former supporters came to feel that, as cruel and violent as the authorities might be, the alternative was even worse. In Chechnya, I remember going see President Aslan Maskhadov in the Chechen capital, Grozny, at the start of the Second Chechen War and noticing that his presidential guard was more worried that I and the party of foreign journalists I was with would be kidnapped than they were by possible attacks by Russian aircraft.

Many journalists who used regularly to visit rebel-held zones in Syria are expressing reluctance to continue doing so. Earlier this year, one internationally known television crew were seized by kidnappers who said they would hold them for three months and ask for $1m in ransom. In the event, they escaped after 10 days. Last year, the NBC chief correspondent, Richard Engel, and his crew were held for five days and were lucky to get free when their abductors unexpectedly ran into a checkpoint operated by another opposition group – there are 1,200 in Syria – and were shot. Reporters Without Borders says it is "aware of a total of 15 cases of foreign journalists disappearing or being abducted in Syria".

Syrian rebels are thus losing the great advantage they had of giving greater access to reporters while the government handed out few visas. The international media may have been credulous in lapping up opposition propaganda, but the government had only itself for blame for creating a vacuum of information that was filled by its enemies.

Even rebel strongholds are no longer safe for visting foreign journalists. Two weeks ago, a Polish journalist called Marcin Suder was kidnapped from an opposition media centre by a gang of gunmen in the rebel-held town of Saraqeb in the north-western Idlib province. An opposition militant who tried to stop the kidnappers was beaten to the ground with rifle butts.

The Syrian opposition is discrediting itself in the same way as insurgents in Chechnya and Iraq. Kidnappings and the inability to provide even basic security alienate people at home and abroad. The methods of a police state begin to appear acceptable if they mean that your children can go to school in safety.