President-elect Donald Trump says Venezuela's embattled opposition leader must be protected as President Nicolas Maduro takes the oath of office for a third six-year term.

Nicolás Maduro took the oath before parliament, vowing his third six-year term in office would be a "period of peace".

Venezuela's authoritarian President Nicolás Maduro was sworn in for a third term on Friday, following an election that many in the international community and the opposition considered rigged. State television showed the president of the National Assembly,