A Fine Gael senator and a Channel 4 camera crew have been refused entry to the Sellafield nuclear reprocessing plant in Cumbria.
The refusal came despite a public invitation at the weekend from British Nuclear Fuels (BNFL), Fine Gael said.
Senator Mr Fergus O'Dowd said he was given the invitation at a public forum on Sellafield in Drogheda, Co Louth, at the weekend.
Speaking outside Sellafield today, Mr O'Dowd said: "This raises serious questions about British Nuclear Fuels when after issuing a public invitation to me last Saturday, they retract it 48 hours later.
"This casts a very sinister light over their relations with the Irish public".
"If they [BNFL] are confident about the safety of their plant, they should be welcoming interest from the media and public in their operation", Mr O'Dowd said.
Ogra Fianna Fáil members are due to hand a letter to the British embassy in Dublin in protest at the British government decision to allow the development of the MOX plant at Sellafield.
The Irish Government has begun legal action to stop the new plant over fears its closeness to Ireland poses a threat.
