A telephone conversation, overheard by a TD, suggested that a riot had been planned in opposition to the Shell gas terminal in north Mayo, the Dáil was told.
Minister for Natural Resources Noel Dempsey said: "When the National Oil Reserves Agency Bill 2006 was debated in this House last week, a colleague told me he overheard a conversation involving a man on a mobile phone in Grafton Street last Tuesday or Wednesday.
"My colleague heard mention of the word 'Rossport' and listened to the rest of the conversation, which basically involved the man telling the other person to be ready to go down on Friday because a riot would take place. I have no reason to doubt the honesty of the deputy who told me this story." Mr Dempsey said that the local people protesting on "non-media days" had, by and large, engaged in peaceful protest.
"They have had no problems with the gardaí on the days on which they have been protesting. However, one can see calls for days of action every day on such websites as Indymedia and the website belonging to the Shell to Sea campaign."
Dr Jerry Cowley (Ind, Mayo) accused the Minister of making an "unfortunate accusation".
He added: "He made allegations about some of the activities in which I am involved. These activities involve my standing up for my constituents who elected me." Dr Cowley said the protest would continue. "This is not a threat. It is a reality." He added that people had come from outside the area to support the campaign, "but the people involved in protests, including the one that took place the last day, are inevitably local people".