In an Austrian prison 25 years ago, a team of foreign monitors heard repeatedly from prisoners who had been beaten in police custody. Over an eight-day period, serious abuse was exposed in a country where few had imagined it. Protections were subsequently put in place – and Europe’s anti-torture committee was born.

You haven’t heard of them. And yet they can walk into any prison, police station, psychiatric ward or immigration detention centre at a moment’s notice. Their interventions have helped stop degrading practices across the continent. Immigrants chained to metal hooks on the floor. Prisoners kept underground for months pre-trial, with no access to natural light and no idea whether it is night or day. As recently as 2008, a visit to a police station in Northern Ireland found evidence of police tying distraught individuals, naked, to their chairs, apparently to prevent self-harm – a practice we insisted must stop.

These are important successes. The anti-torture committee is part of the Council of Europe – the body I lead that is responsible for defending human rights across 47 European states. Thanks to many willing politicians and countless activists, much progress has been made. But there is still a great deal to be done.

It is now well known that a number of European states were complicit in the abuses conducted by the CIA in the hunt for al-Qaida after 9/11. Less understood is current ill-treatment at the hands of European police and prison officers.

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Most worrying is the persistence of police brutality in custody, often to extract a confession. Electric shock treatment. Asphyxiation by plastic bag. The stringing up of suspects by their hands, barely able to breathe while they are punched and kicked. We know this still goes on.

I urge all European states to recommit to erasing torture from our continent. Criminals owe their society a debt and it is right that they are punished for their deeds. But to quote Nelson Mandela: “a nation should not be judged by how it treats its highest citizens, but its lowest ones.”

This is also a matter of security. As governments across Europe now grapple with the problem of radicalisation among prison inmates, state authorities must uphold the highest standards. Torture in our cells will only feed terror on our streets. Treating people like animals is the surest way to help their humanity disappear. For the sake of our shared values and collective security, we must guarantee basic human rights for anyone in state detention.

The Council of Europe is a vigorous watchdog and we will continue to help our members reform, but we cannot be everywhere at once. National governments must now take greater responsibility, with oversight bodies that are independent and have real expertise. Inspection is a sensitive business. It takes careful handling to protect prisoners and whistleblowers from reprisals once the monitors have left.

As more states develop their capacity for self-inspection, the UK will be important. It is in a unique position to show others the way.

When we first came here in the 1990s we found a police force acting as its own judge and jury. The current system is not without critics, but no one can deny that the creation of the Independent Police Complaints Commission> has changed the landscape dramatically. The England and Wales Inspectorate of Prisons has also been an outrider – the first of its kind on the continent. It’s no surprise that, in developing their own systems, the French and others look to the UK for inspiration.

Of course, things are not perfect. Rising prison populations, reduced staffing levels, a lack of activities for inmates and an increase in suicides are problems that must be tackled. However, the UK has a long tradition of openness and self-scrutiny. As we expect the same of others, it has an opportunity to lead.

In all this, what will be needed is political will. This is the lesson of the past 25 years. In our efforts to unearth torture, the Council of Europe has seen many grave things. But we have also seen what is possible when governments commit to human dignity for all. It’s time to make all of Europe a torture-free zone.