Filmmaker David Bradbury along with his wife and son arrived in India on tourist visas and were about to enter Idinthankarai from Kanyakumari district this morning when police stopped them near Radhapuram police station, they said.
"After interrogations, the three were made to go back, since prohibitory orders were in place," an officer said.
The PMANE has been leading protests against the plant for over a year citing safety concerns.
Commissioning of the first unit of the Indo-Russian project was originally scheduled for December last year, but has been delayed due to the protest.