International search for man who fell overboard in rough seas
The UK Coastguard was alerted by a mayday call from the Apollo 20 miles north west of Orkney at 7am on Monday.
Helicopters from Sumburgh and Stornoway are leading the search, joined by US and French aircraft which are in the area to participate in Operation Joint Warrior.
A spokeswoman for the Maritime and Coastguard Agency said: "The UK Coastguard has been coordinating the search for a missing man after he went overboard from a fishing vessel earlier this morning.
"The fishing vessel made a mayday broadcast at approximately 7am this morning reporting that they had a man overboard 20 miles north west of Orkney.
"The UK Coastguard search and rescue helicopters based at Sumburgh and Stornoway have been searching the area.
"Multinational Naval units who are in north Scotland on a joint training exercise have joined the search operation for a man who went overboard off Orkney earlier this morning.
"Coordinated by the UK Coastguard, a French Dassault Falcon is currently engaged with the search and a US P8 Poseidon fixed wing aircraft is making its way to the search area. The search is ongoing."
UK Coastguard commander Tris Newey added: "Our helicopters, along with the fishing vessel, have been searching throughout the morning in very rough weather and challenging conditions, but so far the missing man has not been located. The search is continuing."
A navy helicopter participating in Operation Joint Warrior also helped with the search for the missing skipper of the Louisa at the weekend.
Chris Morrison, 27, and Martin Johnstone, 29, were both lost when the crab trawler went down south of Barra on April 9. Paul Alliston, 42, remains missing, while Lachlan Armstrong, 27, survived by swimming to shore.