The cultivation of opium and coca is on the increase in rebel-held areas of Afghanistan and Colombia, helping them to fund their activities, the United Nations has warned.
While cultivation of the opium poppy stabilized or dropped in many parts of Afghanistan, five southern regions controlled by Taliban militants produced enough poppy to double the world's opium output between 2005 and 2007, according to the UN Office on Drugs and Crime (UNODC) in its World Drug Report 2008.
On the other side of the world in Colombia, coca cultivation rose by 27 per cent in 2007, though coca leaf and cocaine production were concentrated in just 10 of the country's 195 municipalities.
Afghanistan remained the world's top heroin producer last year while Colombia was the foremost producer of cocaine.
"In Colombia, just like in Afghanistan, the regions where most coca is grown are under the control of insurgents," UNODC executive director Antonio Maria Costa said in a statement.
"In the future, we need to be even more proactive," he said. "Recent major increases in drug supply from Afghanistan and Colombia may drive addiction rates up, because of lower prices and higher purity of doses."
Costa's report said that even though there was a sharp rise in the cultivation of coca in Colombia, the actual cocaine output was unchanged in 2007 due to lower yields. This is because planters have had to grow coca on smaller, remote plots to avoid detection by an increasingly aggressive government.
Global opium production reached 8,870 metric tonnes last year, with Afghanistan alone accounting for 92 per cent of the world's supply of the key ingredient for heroin.
"In the southern areas, controlled by the Taliban, counter-narcotics and counter-insurgency must be fought together," Costa said.
Burma, the world's second biggest opium producer, also recorded an increase in opium poppy cultivation last year and was responsible for most of the non-Afghan heroin.