The firm that provided Venezuela's election technology has cast doubt on the outcome of its polls for a new assembly, saying the turnout figures were "manipulated".
Government-allied electoral authorities say more than eight million people voted on July 30, a turnout figure that has been disputed by the opposition and independent analysts and condemned by many nations in the region and beyond.
In a statement issued in London on Wednesday, Smartmatic, which has provided voting machines to Venezuela for the past decade, said: "Based on the robustness of our system, we know, without any doubt, that the turnout of the recent election for a National Constituent Assembly was manipulated."
Al Jazeera's John Holman, reporting from Caracas, said the development was "a big bombshell".
"It is a blow to the government, but the government is going to continue right on with what they are doing," he said. "For the opposition, this is just more proof of what they were already saying on Sunday."
Delayed by a day
The president also announced that the assembly's installation was being delayed by a day, convening on Friday instead of Thursday in order to "organise it well in peace and tranquility".
The electoral council also must still provide 35 members with their credentials, he said.
The new legislative body is entrusted with rewriting the constitution, overriding other branches of government including the opposition-dominated Congress.
Also on Wednesday, General Vladimir Padrino Lopez, Venezuela's defence minister, appeared on television to affirm his loyalty to Maduro.
"We ask for respect for our democracy, for the way in which we have decided to take the road that we deserve to take in peace, in democracy, with tolerance, without violence and without heading toward a coup," Padrino said.
The US earlier this week hit Maduro with sanctions, and diplomats from the 28 EU countries were meeting Federica Mogherini, EU foreign affairs chief, in Brussels on Wednesday to discuss the bloc's course of action.
"Consultations with member states are ongoing to ensure an appropriate and coordinated response by the EU," said Catherine Ray, Mogherini's spokeswoman, when asked if sanctions were on the table.
"Obviously the whole range of actions are discussed. But our priority is the urgent relief of the Venezuelan people and de-escalation of the tensions.
"We promote a political solution to the crisis and we are ready to further support ongoing regional mediation efforts."
There was opposition from some EU states to any kind of sanctions, which would scupper them as sanctions must be approved unanimously, diplomatic sources said.
The EU states are now working on a common declaration that is expected to be published later on Wednesday.
"The declaration is supposed to mention 'other measures'. But no talk so far on sanctions," a European source told AFP on condition of anonymity.
President Nicolas Maduro called the vote for the Constitutional Assembly in May after weeks of protests fed by anger at his government over food shortages, triple-digit inflation and high crime.
Many people accuse the ruling party of corruption and mismanagement.