Illegal drug cultivation is a key factor in the violence
Armed groups forced at least 270,000 Colombians to flee their homes in the first half of this year, a report by a local human rights group says.
The group, Codhes, says this figure represents a 41% increase on 2007.
Rebels, paramilitaries and drug gangs are all forcing people from their land as they fight for land to grow cocaine, according to Codhes.
But the government disputes the figures, saying the number of displaced people, while worrying, is falling.
According to Codhes, the Consultancy for Human Rights and Displacement, the increase in the number of internally-displaced people in Colombia is the highest since 1985.
The group says 270,675 people were forced from their homes in the first six months of 2008, a 41% jump on the same period last year.
One of the main causes, Codhes believes, is the struggle for control of land for illicit drug cultivation, and the rearming of paramilitary fighters.
Codhes also says that rebels of the Revolutionary Armed Forces of Colombia (Farc) have suffered significant blows this year.
But the rights group says the guerrillas still operate in various regions, where they threaten the civilian population and carry out forced recruitment, particularly of minors.
The Colombian government has rejected the figures produced by Codhes, arguing that the number of people being displaced is actually falling.
According to government figures, 110,000 people were forced from their homes in the first half of 2008.
"Although the figures regarding displacement are highly worrying and justify the important efforts the government is making to tackle the problem, they are a far cry from the almost apocalyptic account portrayed by Codhes in its statistics," a government statement said.
Officials challenged the way Codhes compiled its figures, which included, they said, people taking part in marches against forced eradication of the coca crop.
The government statement also pointed to what it said was fraud in the registering of displaced people.
The Colombian authorities put the total number of displaced people at more than 2.5 million.
Codhes believes the real number may be nearer four million, saying many of those forced from their homes do not report it to the authorities as they are threatened by the warring factions.