It is not viable for Venezuelan opposition leader Edmundo Gonzalez to enter the country, his ally Maria Corina Machado said on Friday, shortly after President Nicolas Maduro was sworn in for a third term despite months of controversy over the country's contested July election.

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.

Maria Corina Machado, a 57-year-old engineer with rock-star appeal, became the fearless figurehead of Venezuela's opposition after being barred from challenging strongman Nicolas Maduro in elections last July.