You know the feeling when you find a place that you just can't leave? Well, a survey, of sorts, of more than 2,500 British citizens this week reveals the places that keep us captivated. Or, more precisely, keep us captive: the Foreign Office has released figures presenting a snapshot of the 2,582 UK citizens in prison abroad.

The table of top lockers-up shows America, where 669 are incarcerated, is the land of inopportunity for the largest number of Brits; 357 are in Spanish slammers; Australia (271) and France (133) complete the chain-gang of four. Many of the inmates are from these nations' substantial British expatriate communities, but a significant number will be holidaymakers. And when you calibrate the figures with the total number of British visitors each year the results are startling.

I have compiled an international "Imprisonment Index" comparing the prison population in eight countries with the popularity of the destination. (To check my working: divide the number of UK detainees for each country by the annual visitor figures, then multiply by one million to get a usable index.)

The US index is 100, meaning that for every 10,000 Brits who visit America each year, one is in custody. Thailand takes a harder line – or perhaps UK citizens behave less well in South-east Asia – with an index of 150. The UAE scores a surprisingly modest 40, given the amount of publicity about immodesty and immorality in Dubai.

Spain, the most popular destination for UK travellers, scores a benevolent 20. But to maximise your chances of passing freely without let or hindrance (as the Foreign Secretary, David Miliband, "Requests and requires in the Name of Her Majesty" in every British passport), go to France: its judiciary has the lightest of touches, with an Imprisonment Index of only 10.

The major tourist destination most prone to imprison Brits may come as a surprise: Australia, with an index of 400. Maybe the authorities' hard line is to make up for all the convict jokes, such as the stock response when asked by an immigration official at Sydney airport if you have a criminal record: "I didn't realise it was still compulsory".

Whether in Canberra or Calais, prison abroad is no joking matter; the charity Prisoners Abroad provides a vital lifeline for Brits in custody abroad, and their families.

Drug tourism is big business, as anyone who has explored Amsterdam will know: the principle business of "coffee shops" has little to do with caffeine and a lot to do with cannabis.

Dutch law on drugs is as cloudy as the atmosphere in Amsterdam's Blue Velvet Coffee Shop. Since the mid-1970s, the authorities have practised gedoogbeleid, a policy tolerating the sale and consumption of small amounts of soft drugs in a bid to keep organised crime at bay. Accordingly, British tourists get stoned with impunity in the Netherlands, ignoring the wealth of art and architecture all around in favour of incoherence and inane giggling.

Almost every other country is a lot less liberal. The Foreign Office says two out of five UK citizens jailed abroad are inside for drug offences – and that proportion rises to 99 per cent in South America.

Brazil rates an Imprisonment Index of 165, while Peru soars to a high (if that is not an unfortunate term for drug offenders) of 435.

Meanwhile, the four British travellers recently arrested for trying to smuggle cocaine out of Colombia may not concur with the country's new tourism slogan: "The only risk is wanting to stay."

Spending time with people doing time

"The most colourful days are Thursdays and Sundays, when hundreds of visitors cram into the complex, filling its corridors and courtyards with laughter." Lonely Planet's Bolivia guide is not describing a market in the capital, La Paz – but a prison.

Inmates of San Pedro jail, including some Brits who have become entangled with drugs in the world's third-largest producer of cocaine, have turned their carcel into a tourist attraction.

"I can help you to visit this famous prison," promises a contributor to Lonely Planet's Thorn Tree forum: "My boyfriend is inside, can make you get in and be your guide." But the Foreign Office warns such tours are illegal, and that "Bolivian prisons are guarded on the outside only – there are no police officers on guard within the prison walls, so if something should happen within the prison, the authorities could not guarantee your safety."