A leading member of the group opposed to the building of the Corrib gas terminal in Co Mayo has been discharged from hospital.
School principal Maura Harrington was being treated for a head injury sustained during a confrontation with gardaí this morning.
Ms Harrington collapsed during a brief confrontation with gardaí when protestors tried to break through a cordon, which was erected to prevent them blocking workers from gaining access to the site.
Protestors who had been standing beside her said she had been pushed by a garda.
Willie Corduff, one of five men from the Rossport area who were jailed last year for 94 days for their protest over the Corrib gas pipeline, described the incident as 'terrible' and said the garda presence should be withdrawn.
A spokesperson for the Garda Press Office told RTÉ News that any complaint that might be made about the incident would be fully investigated.
In a separate development, a man in his 60s and woman in her 30s from the Rossport area are being detained at Belmullet Garda Station after allegations of intimidation were made against them.