Photographs have emerged showing an Orthodox priest taking part in the fighting after government forces attempted to remove activists who were camping on the square.
Workers tried to use cranes to clear the area in the capital but protestors fought back and hurled tyres and other objects at authorities.
Barricades were set fire to as black smoke billowed over the city.
Independence Square was the centre of February's revolution that led to the overthrow of Viktor Yanukovych.
Protestors have vowed not to leave until fresh presidential elections to ensure there is no slip back to previous corrupt regimes.
But the government has said the activists are a 'public nuisance' and should move on.