Georgian police have raided the offices of an opposition party and arrested its leader in an apparent attempt to squelch a wave of mass protests over the decision to suspend negotiations on joining the European Union.

In a sign of a widening crackdown, security agents have searched the offices and homes of prominent activists and opposition leaders who fear the country is turning closer to Russia.

A Georgian opposition leader has been dragged from his party office by police and others have been physically attacked, after the prime minister vowed that organisers of a week of pro-EU protests, which he called "violent actions", would face justice.