The US has asked the Colombian authorities to arrest and extradite six right-wing paramilitary leaders and 23 alleged drug traffickers.
The AUC is on Washington's list of terror groups
The requests came from US deputy assistant attorney-general Mary Lee Warren during a visit to Bogota.
Those on the list include the head of the United Self-Defence Forces of Colombia (AUC), Salvatore Mancuso.
Leaders of the 20,000-strong AUC are engaged in faltering peace talks with the Colombian government.
Last week, Colombia's peace commissioner, Luis Carlos Restrepo, said that AUC paramilitary commanders would not be detained or extradited if they moved to a zone in the northern province of Cordoba.
However, peace talks are deadlocked over the paramilitaries' insistence on an amnesty for their crimes.
The BBC's Jeremy McDermott in Colombia says most of the AUC leaders are accused of being drug traffickers and several already had outstanding extradition orders to the US, which they are keen to avoid.
Apart from the AUC leaders, the US is also seeking the extradition of drug-traffickers including two men believed to be the main leaders of the Norte del Valle drug cartel.