* 106,000 followers sign up to Chavez page in two days

* Venezuelan president urges allies to start tweeting too

* Man accused of text death threat against Chavez (Adds text threat arrest)

CARACAS, April 29 (Reuters) - Delighted at his cyber success, Venezuela’s new Twitter convert President Hugo Chavez on Thursday invited Cuba’s Fidel Castro and Bolivian President Evo Morales to join the micro-blogging site too.

After several months grumbling that social networking sites in Venezuela were dominated by opponents of his socialist government, Chavez opened his own account this week and was clearly elated to have gathered 106,000 followers in two days.

“The potential this has ... it’s not capitalist, it’s not socialist, it depends on how it is used,” he said after posting two messages on his page @chavezcandanga.

“I invite Evo and Fidel,” Chavez said. “Evo - are you on Twitter? Let’s invite Evo to Twitter,” Chavez said during a visit to a cattle ranch with Bolivia’s president.

Both Morales and Castro are close allies of Chavez and the three men are Latin America’s most vocal critics of what they call the U.S. empire.

“This has been an unexpected explosion. Thanks,” Chavez said in his second tweet.

Critics of Chavez say he plans to follow Cuba’s lead and censor the Internet, a charge the president denies.

“I don’t criticize anybody, here we are promoting the Internet,” he said on Thursday. Internet use has blossomed in Venezuela during his 11-year rule, especially among the poor.

Many Venezuelans laughed when Chavez announced he would join Twitter, wondering how their famously verbose leader, who speaks almost daily for hours on end, will keep to the service’s 140-character limit.

Chavez’s page name includes “candanga,” which translates locally as a rebellious or strong-willed person.

Separately, a 29-year-old Venezuelan was arrested on Thursday in connection with text messages calling for the assassination of Chavez, authorities said.

Interior Minister Tareck El Aissami said the man was detained in Merida, a city near the border with Colombia, along with computers and other materials.

“Death to Hugo Chavez, for a fatherland free of tyrants,” read the text, according to the minister.

He said the message was attributed to an illegal paramilitary group, the AUC or United Self-Defense Forces of Colombia, which began disarming a few years ago.

El Aissami said the incident showed the constant risk to Chavez from “the Venezuelan bourgeoisie, the U.S. Empire and its trans-national agencies.”

Chavez, who is Latin America’s leading critic of Washington, frequently accuses the Colombian government of being a U.S. pawn in the region. But critics say he exaggerates the threat to distract Venezuelans from domestic problems.