Northern Ireland police say they have arrested three suspected Irish Republican Army dissidents over a suspected car bomb in Londonderry.
British Army engineers are examining Monday's potential bomb at a road junction on the city's outskirts. The alert has caused traffic jams along Northern Ireland's border with the Irish Republic.
The three men aged 46, 49 and 56 are being questioned at the main police interrogation center near Belfast.
Police reported a second suspected bomb in the border town of Newry. It was found on a road running underneath the main Belfast-Dublin highway and near the town's train station.
Several IRA splinter groups seek to force Northern Ireland from the United Kingdom. They reject the IRA's 2005 decisions to disarm and renounce violence.