Despite the demobilization of Colombia's illegal paramilitary groups -- deemed terrorist groups by the U.S. government -- labor leaders continue to be killed, disappeared or threatened in Colombia, the human rights group Amnesty International reported Tuesday.

In its report, titled Killings, Arbitrary Detentions and Death Threats -- The Reality of Trade Unionism in Colombia, Amnesty International describes a pattern of systematic attacks against trade unionists involved in labor disputes, campaigns against privatization or in support of workers' rights in some areas where mining, gas and oil industries operate.

''Amnesty International considers that a coordinated military-paramilitary strategy designed to undermine the work of trade unionists continues to be pursued both through their physical elimination and by seeking to discredit the legitimacy of trade union work,'' the report said.

The New York-based Amnesty International called on global companies to press the Colombian government to end the abuses.

''This report is a wake-up call for any multinational company operating in an environment in which human rights are systematically violated. Inaction is no longer an option,'' said Paul Paz y Miño, Colombia's country specialist for Amnesty International.

The report said that paramilitary groups were responsible for 49 percent of the human rights abuses against Colombia trade unionists in 2005; government forces were blamed for 43 percent and leftist guerrilla groups were responsible for just over 2 percent of the killings in cases where responsibility could be ascertained.

The report said that in 90 percent of the cases, those responsible are not brought to justice and that efforts by the Colombian government to protect trade unionists have been ineffective.

According to Colombia's National Trade Union School, there have been 2,245 killings between January 1991 and last December.

The killings of labor leaders and the lack of prosecutions has become the biggest obstacle to approval of a U.S.-Colombia trade agreement.

The Colombian government has insisted that the number of killings has fallen in the last two years and that the situation is improving.