MINSK -- Vast crowds of protesters flooded Belarus' capital of Minsk on Sunday in the largest political demonstration in the country's history, demanding that its authoritarian leader, Alexander Lukashenko, step down.

Demonstrators in the capital were estimated to number well over 100,000.

Thousands more protested in towns and cities across Belarus, building on the movement that has been growing since last weekend's contested election and posing a colossal challenge to Lukashenko, known as "Europe's last dictator," who has ruled the former Soviet country for 26 years.

In Minsk huge processions of people, cheering and carrying red and white flags, converged on a monument known as the Stele, which just last week police violently kept them from reaching -- part of the brutal crackdown that has seen thousands detained and hundreds injured.

On Sunday the police had withdrawn entirely as the sea of demonstrators swamped the city center. The only police in sight were a handful of traffic officers struggling to direct traffic amid the jubilant crowds and as drivers honked and passengers hung out the windows.