The US adviser on Northern Ireland said his government has become wary of Sinn Féin following alleged IRA links with rebels in Colombia.
Mr Richard Haass told the BBC's
Hard Talk
programme that the claims that the IRA has provided training to the Revolutionary Armed Forces of Colombia, or FARC was of great concern.
"There are things that the FARC is now doing, or things that they did not do previously, and I am told by weapons experts... That many of these things bear certain patterns, or hallmarks of IRA operations," he said.
"Yes, there is what you might call a prima faciecase or an apparent case that clearly there was training that went on that made a difference," he added.
Three Irishmen arrested in Colombia last August, Mr Jim Monaghan, Mr Martin McCauley and Mr Niall Connolly, are currently in a Bogota jail charged with teaching the rebel forces bomb-making techniques.
Mr Haass said the US wanted to see the IRA "get out of the paramilitary business".
"What you're hearing from Americans, even Americans who have been full square supporters of Sinn Féin, is the time is past for that. You now have to become normal," he said.