Venezuela's chief prosecutor was fired today and ordered to stand trial, less than 24 hours after a newly elected legislative superbody was installed with sweeping powers to strengthen President Nicolas Maduro's grip on power.

The prosecutor, Luisa Ortega, had become Maduro's main challenger from within the ruling socialist movement since the opposition started a round of protests in April. The street marches have left more than 120 people dead as rock-throwing protesters were met by rubber bullets, water cannon and tear gas.

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She accused him of human rights abuses and of exaggerating the turnout in last weekend's election of the new 545-member constituent assembly. The opposition, in control of the country's traditional congress, boycotted the vote. This guaranteed that all candidates for the new body would be Maduro allies.

Nicolas Maduro (right) is tightening his grip on power. Photo: Reuters

His loyalist Supreme Court sent a letter to the assembly informing it of an indictment against Ortega, accusing her of "alleged commission of serious misconduct," without further outlining the charge.

Earlier in the day, Ortega's office was surrounded by armed National Guard officers who refused to let her enter. Ortega told reporters she was roughed up as she tried to enter her office, claiming that one officer hit her with his body shield. She left on a motorbike amid the chaos.

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Also today, South American trade bloc Mercosur indefinitely suspended Venezuela, adding to international pressure on Maduro to dismantle the newly created assembly and restore democracy.

The constituent assembly replaced Ortega with Maduro's human rights ombudsman, Tarek Saab, a government ally who the opposition says has turned a blind eye to state abuses.

Swing towards dictatorship?

The new legislative body has no checks on its powers, and critics say the decision to remove Ortega is an ominous sign of a swerve by Maduro into full-blown dictatorship.

The pro-government legislative assembly has been given sweeping powers. Photo: Reuters

Critics blame Maduro's state-centric policies for pushing Venezuela into an economic crisis marked by triple digit inflation and severe shortages of food and medicine.

Maduro says the US "empire" is waging economic war on Venezuela and refuses to allow humanitarian aid to enter the country. He says the new assembly is the only way to unify Venezuela into a peaceful, prosperous socialist state.

The assembly will function for up to two years, according to a resolution it passed on Saturday. The body's stated goal is to lock in the policies of late President Hugo Chavez, who put Venezuela on its socialist path when he was first elected nearly two decades ago.

It will hold its sessions in the same legislative complex as the traditional congress, which could potentially be dissolved. For now, the two bodies are set to hold sessions in parallel, separated by an ornate cobblestone courtyard.