Jorge Parrado collects water for his Caracas district. But he is also ready to fight completely in support of President Nicolas Maduro as a member of a "colectivo," cells that uphold and enforce the regime's socialist ideals.

He had arrived at a park in the west of the capital aboard a water tanker to fill it from wells. The precious water was to be taken to clinics close to the working class district of El Cementerio.

The scene occurred during a weeklong blackout that was the worst in Venezuela's history. The outage disrupted transport, fuel and -- most importantly -- water supplies.

Maduro had called on his supporters to show "active resistance" to the "electric sabotage" he claimed was waged by the United States. He urged the colectivos to rally around.

"The president called us into the streets as colectivos, but we were already out and about for five days. There's no point calling on us because we are always ready to fight, whatever it takes," Parrado told AFP as he waited for the wells to be free.

Aged 43, he belongs to the "Che Guevara" colectivo, which he joined after the previous and late leader Hugo Chavez enacted policies that Parrado said allowed him to leave a life of crime.

"It was hard times and Chavez got me off the streets. Since then I'm totally behind the revolution," he said.

- Known for attacks -

People fill up water buckets set to be distributed by the government to hospitals and various Caracas neighborhoods YURI CORTEZ, AFP

Yet the term "colectivo" is feared by many in Venezuela who associate it with gangs of armed pro-government thugs who target opposition sympathizers.

Seen riding around on motorbikes in groups, often carrying weapons and wearing hoods, they plunge into demonstrations to sow what their detractors call "the Bolivarian circus."

Such attacks were notably seen on February 23 on the borders with Colombia and Brazil, when colectivos descended on supporters of Juan Guaido, the head of the opposition-ruled congress who has proclaimed himself interim president with the backing of the US and 50 other countries.

On that day, the colectivos acted to prevent the entry of US aid that Guaido and the opposition had tried to drive into Venezuela. Seven people were shot dead and at least 300 wounded, according to the opposition.

The bloodshed, which Washington attributed to "Maduro's killers," was condemned by United Nations High Commissioner for Human Rights Michelle Bachelet.

Bachelet said the overt use of "paramilitary forces" in Venezuela was "worrying" and could exacerbate already high tensions in the country.

But some, such as Ysmar Sanchez, coordinator of the Bolivarian Socialist Front for Defense and Protection, denied that the government was arming the colectivos, though he did acknowledge that their members included soldiers and police officers.

Sanchez said part of his organization was tasked with rooting out ordinary criminals who tried to pass themselves off as colectivos.

"Our task is above all aiding society, but we are also a fighting force when it comes to defending the homeland. If violence happens we come out to put an end to it," he said.

- Hard to control -

Analysts warned that, in the tinderbox that is Venezuela today, the colectivos could cause a spark triggering a conflagration.

"The colectivos exist for various reasons. They carry out educational, farming, productive, artistic and sporting activities," said Pedro Afonso del Pino, a professor in constitutional law at the Central University of Venezuela.

"There are probably all sorts. But among them there are many that are involved in political violence."

Should the United States decide on military intervention in the country, the colectivos could rise up to employ uncontrollable violence, in the same way as was seen in Syria or Libya, said another political analyst, Luis Vicente Leon.

Del Pino said that bringing the colectivos to heel would prove to be "one of the challenges" of any new government replacing Maduro's.

"They will have to decide what to do about these groups, whether to keep them or not," he said. "If a transition fails to address at least a number of them it will be difficult to control these groups."