Colombian security forces killed civilians in several states last year and falsely labeled many as leftist rebels slain in combat, the United Nations said a report released Thursday.

The report said leftist rebels, right-wing paramilitary groups and, to a lesser extent, government forces were all behind frequent human rights abuses, including torture, executions and disappearances. The three sides have been pitted against each other in a half-century-old civil conflict.

The U.N. said the numbers of civilian killed in those areas showed an increase over 2005 but did not provide death toll figures.

The report said such killings with "characteristics of extrajudicial executions do not appear to be isolated incidents" and may have been prompted partly by the government‘s use of combat deaths as a benchmark to measure success against leftist insurgents.

"We believe progress has been made," Corlazzoli said, praising Colombian officials for showing "greater commitment" to reducing abuses.

Corlazzoli said his office received 2,138 complaints of human rights abuses last year, roughly the same number as 2005.

The report said security forces had taken no action against police or soldiers believed to have links to such groups.