Police in Northern Ireland are dealing with a security alert on the rail line between Lurgan and Moira.
The PSNI said no further information was available.
Iarnród Éireann said services on the line will be substituted by bus between Newry and Belfast and there will be delays of up to 45 minutes. The rail firm apologised to customers for the inconvenience.
Meanwhile, the departures road at Dublin Airport will be closed to traffic for seven hours from about 8.30pm tonight until 3.30am on Tuesday morning.
The arrivals road will be closed for four hours from 11.30pm until 3.30am.
Cars will be able to drop departing passengers at a set-down zone behind the rear of the multi-storey car park. Additional customer service staff will be on hand to direct passengers, the Dublin Airport Authority said.
Taxis and buses that normally use the arrivals road will be diverted to the rear of the multi-storey car park. Access to both the multi-storey car parks and the coach park will remain open as normal.