Prosecutors accuse William Parra of crimes including financing terrorist activities and sedition.
Parra was press secretary for then-Colombian President Ernesto Samper in the 1990s and has recently worked with Telesur, the regional TV network backed by Venezuela's leftist government.
Prosecutors say they have e-mails Parra exchanged with Raul Reyes, a rebel commander killed in 2008. They say that in one, Reyes asks Parra to buy missiles in the Middle East.
Parra issued a communique Tuesday declaring his innocence. There appears to be no evidence Parra ever tried to buy missiles.