More than 850 Britons are currently locked up in overseas prisons for drug-related offences, often detained for months without trial and facing distressing living conditions, according to the Foreign and Commonwealth Office (FCO).
The news follows the high-profile cases of Dungannon woman Michaella McCollum Connolly and co-accused Scot Melissa Reid, who are awaiting trial in Peru accused of cocaine smuggling.
With charity Prisoners Abroad, the FCO highlighted the fact that some Britons are serving sentences of up to 39 years, while many still wait for their cases to come to court.
The two organisations are launching a campaign to show the consequences of the use, possession and smuggling of drugs in countries around the world.
The FCO said the zero-tolerance approach of some countries often results in strict penalties which can come as a shock to British travellers. Offences that may carry cautions in the UK are often penalised with long prison sentences when overseas.
Some drug crimes can lead to even more severe penalties, and in 33 countries or territories some drug offences carry the death sentence.
- In Thailand being in possession of in excess of 20 grams of a Class A drug could mean your being deemed as a trafficker and could potentially be sentenced to death.
- United Arab Emirates' sentences for drug trafficking for possession of even the smallest amount of illegal drugs can lead to a minimum four-year jail sentence.
- In Peru more than 30 Britons are currently in prison for drugs offences. Drug smugglers in the country face long terms of imprisonment.
- In Indonesia, those caught with drugs face lengthy prison sentences or the death penalty, usually after a protracted and expensive legal process.
Prisoners Abroad is currently supporting 80 Britons between the ages of 18 and 30 held in foreign countries for drugs offences. Two thirds of these are still awaiting trial while others are serving sentences from a year to nearly 39 years.
Consular affairs minister Mark Simmonds said: "People continue to be astonished at some of the penalties handed down for certain crimes overseas. In some countries possessing small amounts of marijuana can lead to decades in prison.
"In the last year alone consular staff handled over 650 drug-related cases. We want to reduce this number significantly."
He went on: "Laws, penalties and sentences vary considerably around the world for the use, possession and trafficking of all types of drugs. When it comes to drugs our message is clear - don't take risks, the consequences are simply not worth it."
Prisoners Abroad chief executive Pauline Crowe said: "In many countries, men and women find themselves without access to food, clean water and the most basic of medical care.
"We urge people to consider the unsanitary conditions, overcrowded cells and the constant threat of disease before they get involved in drugs. They may have to live through these conditions for many, many years."