The youths, some of whom were mentally or physically disabled, are said to have been classified by authorities as "unidentified" and buried after being allegedly killed by Colombian soldiers.

"Innocent people in urban slums were apparently tricked, abducted and killed [in] ... a gruesome trafficking in cadavers allowing officers to claim high body counts," said Adam Isacson, a Colombia analyst at the US-based Center for International Policy.

'Clean conscience'

"Innocent people in urban slums were apparently tricked, abducted, and killed".

Adam Isacson, Colombia analyst

Three generals, 11 colonels and three majors were among those relieved of their duties following the probe.

"We cannot allow any violation of human rights," Uribe said during a televised announcement from the presidential palace.

He did not give details of how the officers were believed to have been involved in the disappearances.

General Roberto Pico Hernandez, one of those sacked, told the Associated Press: "My conscience is clean.

"I think this is something unjust because I have worked [and] dedicated everything to my army, including even not taking good enough care of my family."

'Civilians executed'

Uribe has received billions of dollars in US aid to fight guerrillas and presented his military successes as evidence his government deserves a contested US free trade agreement.

He introduced a policy of rewarding soldiers for combat casualties to demonstrate progress in the war on Colombian insurgent groups, Gustavo Petro, an opposition senator, told the AFP news agency.

He said about 1,000 disappearances similar to the current case were reported at a congressional debate three years ago on so-called "false positives" - an alleged army practice of executing civilians to inflate the number of rebel deaths.

Amnesty International a day earlier denounced "false positives" in Colombia, saying 330 people were reported killed in extrajudicial executions by security forces in 2007, most of them falsely presented as guerrillas killed in combat.

'Body count' policies

Susan Lee, Amnesty International's Americas director, said: "At last, the Colombian government is admitting there is a human rights problem in the country and that action needs to be taken to solve it.

"That action should be justice."

The organisation has urged the US and other nations to halt military aid to Colombia until security forces reduce the killing of civilians.

Juan Manuel Santos, the Colombian defence minister, recently acknowledged that officers were pressuring soldiers to show proof of their success in combat and ordered an investigation into unofficial military "body count" policies.

His comments followed public outcry over the disappearance of 19 young men who were recruited near Bogota by men promising them jobs in the country's northeast.

Their bodies were found last month in mass graves.