Four women and three men were arrested following raids on nine brothels and six other locations across Ireland.
This afternoon, another man was arrested by the PSNI in Co Down and a man and a woman were detained by police in Wales.
Welsh police say those arrested are a 47-year-old Irishman and a 31-year-old South African woman.
The four women and three men being held in the Republic are suspected of committing a number of offences including organising and managing prostitution.
Brothels were searched in Cavan, Drogheda, Athlone, Mullingar, Sligo, Kilkenny, Enniscorthy, Newbridge, and Waterford.
Six other locations in the Carlow area were also searched, including the homes and offices of a number of professional individuals.
The raids follow an international investigation into human trafficking which involved gardaí, the PSNI and the British Serious Organised Crime Agency.
The PSNI said the man arrested in Newry was being detained on suspicion of immigration offences.
It also conducted a number of covert inquiries at several locations in Northern Ireland being used as brothels by an criminal gang, organised through the internet.
The PSNI spokesman said it believes it has dismantled an organised crime gang which was operating in three jurisdictions in Europe, and has links to South Africa.
