Colombian authorities say they have arrested a Cuban national suspected of plotting to kill American diplomats on behalf of Islamic State.

The suspect, Raul Gutierrez, appeared in a Bogota court Thursday and was ordered held without bail on terrorism and conspiracy charges. He has pleaded not guilty.

Prosecutors say Gutierrez, who is in Colombia illegally, planned to attack Bogota's exclusive Zona Rosa, a densely populated area frequently visited by American tourists and diplomats.

Colombian authorities began tracking Gutierrez after they intercepted communications from late February in which Gutierrez allegedly discussed plans to make and detonate a homemade explosive.

Spanish police and the FBI had been monitoring Gutierrez for several weeks. They say he showed signs of indoctrination in radical Islam.

Colombian prosecutors said Gutierrez had received precise instructions in communications with people from Spain and Morocco on carrying out an attack targeting Americans.

It is not yet known if Gutierrez is part of the Islamic State network, or merely a sympathizer.