Venezuela's Supreme Justice Tribunal on Thursday ratified President Nicolas Maduro's victory in the July 28 presidential election.

The supreme tribunal has reviewed material from the electoral authority and agrees that Maduro won the election, court president Caryslia Rodriguez said, adding the decision cannot be appealed.

"The electoral material assessed is certified unobjectionably and the results of the presidential election of July 28 released by the national electoral council, where Nicolas Maduro was elected president of the republic, are validated," said Rodriguez.

The electoral authority has said since the night of the election that Maduro won just over half of votes, though it has not published full tallies.

The opposition has published online what it says are 83 percent of voting machine tallies, which give its candidate Edmundo Gonzalez a hearty 67 percent support.

Many Western countries have urged full publication of results, while Russia, China and others have congratulated Maduro on his victory.

The supreme court would be in violation of separation of powers rules in the constitution if it were to carry out any electoral functions, thus making its ruling null, the opposition said in a statement on Wednesday.

The ratification gives Maduro, who took office in 2013, another six-year term, set to begin in January.

The president, a long-time ruling party official before he rose to the presidency, had asked the court to verify the results. The court's judges summoned all the candidates to hand over the copies of voting machine tallies they are entitled to by law.

Gonzalez did not attend the summons. The opposition says the court, though constitutionally independent, operates as an arm of the ruling party.

The opposition's failure to hand over its copies and Gonzalez's non-appearance are "blatant disrespect", Rodriguez said, and exposes him to sanctions, though she did not specify what kind.

At least 23 protesters have been killed at anti-government demonstrations since the election, and some 2,400 arrested, according to the United Nations. Maduro says the demonstrators are extremists. (Reuters)