The detention of Oswaldo Alvarez Paz, a veteran with the opposition COPEI party but not one of Chavez's most prominent foes, will fuel criticism that the Venezuelan leader is taking his nation down an increasingly dictatorial route.
Alvarez joins a list of several dozen Chavez opponents now in jail, living in exile or facing probes in the South American oil-producing country.
With the political atmosphere heating up before legislative elections in September -- seen as a barometer for a 2012 presidential vote -- Chavez says his opponents are increasingly breaking laws in their desperation to topple him.
A court ordered Alvarez's arrest at his home in Caracas late on Monday on charges of conspiracy, spreading false information and inciting hatred, judicial officials said on Tuesday.
He governed oil-producing Zulia state in the early 1990s and unsuccessfully ran for the presidency with COPEI in 1993.