Venezuela's recently created National Constituent Assembly (ANC), a plenipotentiary body made up of allies of leftist President Nicolas Maduro, voted unanimously Friday to take over the powers of the opposition-controlled legislature.

The vote came after the leaders of the National Assembly, the unicameral legislature, refused an invitation to attend Friday's ANC session at the legislative palace.

Venezuela's opposition does not recognize the ANC, calling it an illegitimate tool the Maduro government is using to consolidate a dictatorship.

By decree, the constituent assembly voted to "assume the power to legislate on matters that directly pertain to guaranteeing the preservation of peace, public safety, sovereignty, the socio-economic and financial system, the objectives of the state and the pre-eminence of Venezuelans' rights."

That body said the decree had its basis in Article 349 of Venezuela's 1999 constitution, which states that the existing constituted authorities shall in no way be permitted to obstruct the decisions of a duly-formed Constituent Assembly.

But National Assembly President Julio Borges said in an open letter released Friday that the ANC was not an authentic constituent assembly but rather a "de facto power" set up to keep Maduro in power.

The letter reiterated the opposition's contention that the July 30 election of the ANC's members - a process boycotted by the opposition - was marred by fraud; it put the number of people casting a ballot at 2 million, while electoral authorities say 8 million people participated.

The National Assembly, which has continued to meet at a separate chamber of the legislative palace, called on its members and ordinary Venezuelans to attend a session on Saturday.

While Venezuelan politics have been dominated for nearly 20 years by Maduro and his mentor and predecessor, the late Hugo Chavez, the tide appeared to turn when the opposition won a big majority in the December 2015 National Assembly elections.

But the Supreme Court, which is made up of Maduro appointees, stripped the legislature of its budgetary authority last year, saying it was in contempt for seating lawmakers accused of electoral fraud.

The crisis has only deepened in 2017.

Opposition-led protests stemming in part from a high court decision in March (one that was quickly reversed) to seize the legislature's remaining powers led to more than 100 deaths and prompted Maduro's government to call for the creation of the ANC to rewrite the constitution.

Maduro says that plenipotentiary body is needed to bring peace to oil-rich Venezuela and resolve its severe economic woes, but the opposition and much of the international community say it will be used to strip away all vestiges of democracy in the country.

Since its inauguration earlier this month, the ANC has sacked a key government critic, Attorney General Luisa Ortega Diaz, issued a ruling stating that its decisions override those of any other constitutional bodies in Venezuela and threatened to jail opposition leaders.