With Greek PM Tsipras due to speak any moment, scuffles in the crowds of protesters have broken out and police have resorted to stun grenades and tear gas...

As Reuters reports,

Greek police threw stun grenades and scuffled with protesters in central Athens on Friday, as a rally got under way in support of a 'No' vote in a Sunday referendum on whether to endorse an aid deal with creditors.

The scuffles involved a few dozen people, many dressed in black and wearing helmets but quickly appeared to calm.