Sinn Féin national chairman Mitchel McLaughlin was one of a number of republicans whose personal details were found in the hands of a known loyalist, it emerged today.
A party spokesman confirmed that Mr McLaughlin was contacted by police in Derry last night and advised to review his security.
'There was a number of people contacted last night and told that a senior loyalist had been arrested with their details in his possession.'
A 38-year-old man is due to appear befire Derry Magistrates Court tomorrow charged with possession of information likely to be of use to terrorists.
Sources in Londonderry said the loyalist is a leading member of the Ulster Political Research Group (UPRG). It is believed that when he was stopped by police on Friday he had the details of a republican in his possession.
Police discovered more names and addresses when they searched his home and office.
The UPRG, which was formed last year, is linked to the largest loyalist paramilitary organisation, the Ulster Defence Association.
UPRG spokesman John White expressed surprise at the arrest of a colleague. 'He has certainly made a very positive contribution and I would be very surprised if he was involved in any illegal activity,' he added.
Former Derry City mayor, councillor Pat Ramsey of the SDLP said: 'Obviously it is worrying that people are compiling information.
"Clearly there are those within loyalism intent on carrying on a war aimed at other people in this city. I hope we won't see any attacks.'
PA