Antonio Maria Costa, executive director of the United Nations Office on Drugs and Crime executive, called the Colombian production figures "a surprise and a shock".
"A surprise because it comes at a time when the Colombian government is trying so hard to eradicate coca," he said, "a shock because of the magnitude of cultivation."
Colombia has an eradication programme, backed by a massive US aid package, which destroyed about 210,000 hectares of coca in 2007.
However, coca fields are virtually back to the level of 2002, when Plan Colombia, the joint US-Colombian initiative to fumigate and manually destroy the country's coca, was in its early stages.
The US has spent more than $5bn since 2001 to combat cocaine production in Colombia. The cocaine industry helps to fund an armed campaign against the government that has been running for five decades.
The Colombian military receives about 80 per cent of the aid and about 20 per cent goes to social projects to ameliorate diversification in production.
Production is said to have increased due to quick replanting, and hybrid coca varieties and new coatings limiting the effects of herbicides used by the government to destroy them.
Still, Colombian officials said production had not increased in line with coca planting due to police pressure causing an interruption in the growing cycle.
General Oscar Naranjo, the head of Colombia's police, said: "These young crops, the new ones, are less productive."
He said that Plan Colombia had pushed coca farmers to move to more remote areas of the country where it is harder to get the chemicals needed to make cocaine.
"Just like in Afghanistan, where most opium is grown in provinces with a heavy Taliban presence, in Colombia most coca is grown in areas controlled by insurgents," Naranjo said.