More than one hundred protesters have clashed with the security forces in Dublin.
The scuffles broke out as the demonstrators tried to breach security guarding Queen Elizabeth II on her first state visit to the Republic.
The protest, organised by the nationalist party Sinn fein began peacefully but erupted into violence as the crowd approached the security barricades.
Stones and fireworks were hurled at police.
The demonstrators are opposed to the visit by the British head of state due to the continued partition of Ireland.