Colombia on Tuesday extradited 14 of its nationals, including 13 paramilitary leaders, to the United States to face drug trafficking charges, Justice Minister Carlos Holguin announced.

News reports said the men were taken at dawn to Catam military base near Bogota to be handed over to officials from the US Drug Enforcement Agency.

Media here said the group includes top leaders of the infamous right-wing militias, including Salvatore Mancuso, Rodrigo Tuvar Pupo (alias "George 40"), Diego Fernando Murillo (alias "Don Berna"), Hernan Giraldo (alias Pablo Sevillano) and Ramiro Vanoy.

Many paramilitary fighters demobilized in recent years to take advantage of a law limiting their prison sentences to eight years and protecting them from extradition if they do so.

But the United States has argued that many paramilitary leaders continued their drug trafficking activity from behind bars.

The 14 extradited Colombians failed to respect requirements of the law, lying to authorities and failing to declare assets to be used to pay damages to victims, El Tiempo newspaper reported, citing government sources.

Paramilitary groups first formed 30 years ago to protect landowners from leftist rebel groups and at times numbered as many as 31,000 fighters.

The groups rely on drug trafficking, particularly cocaine, to finance their activities, and they have been linked to civilian massacres and the murders of leftist politicians, union leaders and journalists.

In recent years investigations have revealed extensive links between paramilitary leaders and officials currently in government.

President Alvaro Uribe himself was in the spotlight late last month, denying charges he helped plan a 1997 massacre by right-wing paramilitaries, while confirming that his role was being examined in an official probe.

Uribe said the charges were lodged by a former member of the paramilitary, whom he described as a disgruntled convict with an axe to grind.

"He said I was at a meeting with him ... along with various generals in La Caucana, taking part in planning the massacre at Aro," in which 15 people were killed, Uribe told Colombian broadcaster Radio Caracol.

But Uribe said he had proof of his innocence, and lashed out at justice officials for following up the accusations against "honorable people."

The Supreme Court investigation into links between politicians and the right wing paramilitary group United Self-Defense Forces of Colombia has been going on since 2006, since documents were discovered on the computer of a leader of the group which indicated the existence of alliances with legislators, governors and other officials.

The investigation has linked 62 current and former politicians to the paramilitaries; 31 have been jailed so far.

The current president of Colombia's federal legislature, Nancy Gutierrez, is among the officials currently under investigation for alleged paramilitary ties.

The issue of Uribe's alleged links to the murderous group has led to US lawmakers holding up the Colombia-US free trade pact.

Uribe revealed the existence of the investigation one day after his cousin, former senator Mario Uribe, sought, but was denied, political asylum in Costa Rica's embassy here.

Mario Uribe on Tuesday asked the embassy for protection after Colombian prosecutors ordered his arrest for alleged ties to right-wing paramilitaries.

He presided over Colombia's senate until October 2007, when a Supreme Court investigation uncovered information linking him to land purchases from the paramilitaries.