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Maduro sworn in as Venezuela's acting president

Juan Barreto / AFP - Getty Images

The President of the National Assembly, Diosdado Cabello puts the presidential sash on Venezuelan Vice President Nicolas Maduro after he was sworn in as President in Charge, in Caracas, on March 8, 2013.

Venezuela's Nicolas Maduro was sworn in as acting president Friday, against objections from the country's political opposition that the move violates the country's constitution. Maduro named as his vice president the son-in-law of the late President Hugo Chavez.

Chavez had hand-picked Maduro, his vice president, as his successor before he died of cancer Tuesday.

Opposition leaders said the swearing-in violates the constitution because Chavez was never sworn in after he won re-election last fall. The socialist leader was too ill at the time.

"I want the world to know that this is a fraudulent swearing-in," said Henrique Capriles, the opposition leader who ran against Chavez in the October elections. He added that Venezuela's presidency should not be achieved by decree.

According to the country's constitution, the National Assembly speaker should become interim president if a president-elect dies without having been sworn in.

Maduro is a former bus driver and union leader who now leads the Chavista movement. This week, Maduro blamed "enemy countries" for Chavez's cancer.

The constitution stipulates new elections should be called within 30 days. Maduro called for a snap election in a few weeks. Officials are expected to announce a date on Saturday, Reuters reported. 

Maduro's new vice president is Jorge Arreaza, who is married to Chavez's daughter María Gabriela. Arreaza has been the Venezuelan government's science and technology minister.

NBC News' Erika Angulo contributed to this report.

Leaders from just about every country in Latin America, as well as Iran President Mahmoud Ahmadinejad and a small delegation from the U.S., turned out for the funeral of Venezuelan President Hugo Chavez. NBC's Mark Potter reports.