A US naval ship, Virginia Ann which has been conducting operations in Irish territorial seas for the past four months with its Automatic Identification System (AIS) transmitter turned off is causing concern among Irish defence officials.

The advanced offshore supply ship reports The Irish Times, which is fitted with equipment capable of subsea operations, had departed Cork Harbour in the early hours of Thursday morning.

Afloat adds the 3,518 gross tonnage vessel had berthed at Rushbrooke (near Cobh) to be resupplied and further downriver along the quay the decommissioned Coastal Patrol Vessel (CPV) twins LÉ Orla and LÉ Ciara which await disposal.

The US naval ship which features cranes amidships and stern-mounted is currently sailing west offshore of Mizen Head.

Virginia Ann which was built in 2015 is according to the newspaper, operated by the US Naval Facilities Engineering and Expeditionary Warfare Centre or Navfac-EXWC.

More on the story here on the naval visitor that is understood to be capable of advanced subsurface operations, including the deployment of deep-sea divers from the 86m vessel.