Colombia signs international criminal court treaty
"There is no place of refuge in this world for those who degrade human life and mercilessly attack their peers," Mr Pastrana said.
"Whoever insists in attacking the civilian population and act outside of international humanitarian law will be captured, tried, and sentenced."
Colombia's conflict claims about 3,500 mostly civilian lives a year, and pits the FARC Marxist rebels against far-right paramilitary outlaws and the army. Analysts say any eventual peace deal would likely involve an amnesty accord for the country's outlawed fighters.
There are currently three Irishmen in prison in Colombia awaiting trial on charges of training FARC troops.
The UN-administered ICC would be the first permanent world tribunal to prosecute people for war crimes, genocide and crimes against humanity. A timetable for the court to start functioning is expected to be fixed in July.