Venezuela has been engulfed by violent riots as opposition candidate Edmundo Gonzalez Urrutia announced he has proof he won Sunday's disputed election hours after President Nicolas Maduro claimed he'd secured a third term in power.

Thousands of enraged protesters flooded the streets of the capital and several other cities, chanting 'Freedom, freedom!' and 'This government is going to fall!' as they set fire to tyres and rubbish and organised barricades to block police vehicles. 

Security forces fired tear gas and rubber bullets into the crowds but were forced to recoil from Molotov cocktails and rocks hurled by the oncoming demonstrators, many of whom carried Venezuelan flags.