A helicopter with five people on board has gone missing over Caernarfon Bay in north Wales.
The privately-owned helicopter is believed to have left Milton Keynes earlier on Wednesday en route to Dublin.
The UK Coastguard said radar contact was lost on Wednesday afternoon.
Two UK Coastguard helicopters searched the area between north Wales and the shore of Dublin before returning to their bases for the evening.
North Wales Police has been notified of the search operation for the twin squirrel red helicopter.
A Mayday broadcast has been issued to all vessels passing through the Irish Sea route to contact the UK Coastguard if they have seen anything.
Earlier on Wednesday, UK Coastguard duty commander Peter Davies said: “We have established a search plan between Caernarfon Bay and the shore of Dublin and currently have two coastguard helicopters searching the route.”