Venezuela’s chief prosecutor, an ally of President Nicolas Maduro, has said the decision by the Supreme Court to take over legislative powers from the National Assembly violates the law.
Luisa Ortega is the first high-ranking official to criticise the measure. She has expressed “great concern”.
The ruling effectively dissolves the elected legislature, which has been dominated by the president’s opponents.
Critics say the “coup” takes the country closer to one-man rule.
The Organisation of American States (OAS) described the development as the “final blow to democracy in the country”.
In her annual report, Ms Ortega said: “[The measure] constitutes a rupture of the constitutional order. It’s my obligation to express my great concern to the country.”
The statement is a surprising break with the official line for someone close to the government and may be seen by some as evidence of fissures appearing in Mr Maduro’s base, BBC Latin America correspondent Will Grant says.
What has happened?
On Thursday the Venezuelan Supreme Court seized power from the opposition-led legislature, a move that could essentially allow it to write laws itself.
The court justified the move by saying the National Assembly’s lawmakers were “in a situation of contempt” after allegations of electoral irregularities by three opposition lawmakers during the 2015 elections.
It did not indicate if or when it might hand power back.
The court had previously backed the leftist president in his struggles with the legislature – on Tuesday removing parliamentary immunity from the assembly’s members.
The move is the latest example of the socialist President Maduro tightening his grip on power, which critics say he has been doing for months, amid a deepening economic crisis in the country.
What has the reaction been?
The crisis has raised international alarm about the stability of Venezuelan democracy, which has undergone three attempted military coups since 1992.
The US state department called the court’s move a “serious setback for democracy”.
Most regional powers including Brazil, Mexico, Argentina, Peru and Chile have warned that the action is a threat to Venezuelan democracy. The regional bloc Mercosur will discuss the situation at an emergency meeting on Saturday.
Leftist-led Bolivia defended President Maduro, who has yet to comment publicly.
Venezuela’s foreign ministry accused critics of the government of forming a right-wing regional pact against President Maduro.
Foreign Minister Delcy Rodriguez described the OAS is a pawn of US “imperialism”.
On Friday, police and soldiers with riot shields pushed back dozens of protesters who joined anti-government marches in Caracas.
Why is Venezuela in crisis?
Tensions have been high in Venezuela because the country has been engulfed by a severe economic crisis.
It has the world’s highest inflation rate, which the International Monetary Fund predicts could reach 1,660% next year.
The government and opposition blame each other for the country’s economic problems, made worse by the falling prices of oil, Venezuela’s main export product.
President Maduro has become increasingly unpopular, and the opposition has called for his removal from office and fresh elections.