Colombian authorities are searching for six members of the Basque separatist group ETA and the Irish Republican Army.
It is reported they are suspected of taking part in the bombing of the upmarket El Nogal club in Bogotá two weeks ago that left 36 dead.
The attack, which also injured 160 people, was blamed on FARC rebels.
They have recently stepped up urban attacks and are increasingly targeting the country's upper middle classes.
A former FARC member is said to have told investigators that the ETA and IRA members entered Colombia along its 2,219 km border with Venezuela.
Investigators believe more than 150 kg of C4 explosive and ammonium nitrate were used in the blast.
Police were investigating whether the bombing was planned with the help of one of more of El Nogal's 400 employees.