Mass rallies in defense of leader facing impeachment

Rousseff accuses enemies of mounting a 'coup', as her supporters demonstrate in 30 cities

Supporters of Brazilian President Dilma Rousseff called mass street rallies on Friday in her defense, counterattacking in a political crisis that threatens to drive her from office.

As police fired tear gas and stun grenades to keep at bay angry protesters demanding Rousseff's resignation late on Thursday, her embattled left-wing support base mobilized.