Clashes broke out on Friday evening in Athens' Syntagma Square ahead of a rally backed by Prime Minister Alexis Tsipras to galvanize support for the "no" campaign ahead of Sunday's referendum on Greece's debt deal. The police used pepper spray against dozens of anti-establishment protestors who had gathered before the rally, throwing rocks and destroying property 800 meters away from the site where the "yes" side was holding its competing rally.

The unrest broke out less than an hour after Greece's highest adminsitrative court, the Council of State, ruled against two private citizens who had launched a suit against the bailout referendum. They had argued that the vote was illegal, saying that Greece's consitution prohibits popular votes on financial issues.

The court decided that the "the referendum will proceed normally." but has not yet given its reasoning.

Huge crowds flood central Athens for rival rallies

Police estimated that the no and yes rallies brought 25,000 and 20,000 supporters, respectively, out into the capital's streets.

The "no" demonstration was addressed by Prime Minister Tsipras, who has been vocal in his insistence that a no vote does not mean Greece will leave the eurozone or the EU. Instead, he says that it would allow a renegotiation that may yield better terms for Greece.

Tsipras received wild applause and cheers from supporters as he made his way from his office to Syntagma Square.

In his second public address of the day, Tspiras called on the crowd to make a decision about living "in Europe with dignity." He said Greece would not abandon Europe to "the hands of those who want to drag her away from her democratic traditions."

Greeks "have justice on our side and we will win" Tsipras added.

Polls on the issue have varied considerably in recent days. Two published on Friday offered similar results, however, suggesting that the two sides were effectively tied. An Alco Institute survey on Friday put the no camp at 44.8 percent and the yes voters at 43.4, with the remainder undecided. A Bloomberg survey had relatively similar numbers, also with "no" ever so slightly ahead. Both polls had unusually high margins of error, in excess of 3 percentage points.

es/msh (AP, AFP)