The Royal Navy has finally admitted one of its submarines damaged an Irish fishing trawler in April - five months after a Russian vessel was blamed for the incident.

The Karen was towed at 10 knots during the April 15 incident 18 miles from Ardglass on the south-east shore of Northern Ireland and the vessel was left badly damaged, but the crew escaped unharmed.

Nato exercises were held that week in northern Scotland leading to speculation that the alliance's drills may have attracted Russian interest.

Captain Paul Murphy holds up a snapped steel cable aboard his boat. The damage was initially thought to have been caused by a Russian submarine but it was actually a Royal Navy vessel which caused the damage

The incident happened off the coast of Northern Ireland and was the second time in two months that fishermen have reported being dragged by a suspected submarine (file picture)

The 60-foot boat's captain Paul Murphy was pictured holding a snapped steel cable on board his boat following the alarming incident.

At the time the Navy said none of its submarines were in the Irish Sea and Armed Forces Minister Penny Mordaunt told Parliament a UK vessel was not responsible.

Now Ms Mordaunt has been forced to make a U-turn and revealed it was in fact a British submarine which snagged the boat.

Ms Mordaunt said: 'The Royal Navy has now confirmed that a UK submarine was in fact responsible for snagging The Karen's nets.

'The incident, the delay in identifying and addressing the events on that day, and their consequences are deeply regretted.

'It is standing Ministry of Defence (MoD) policy not to comment in detail on submarine operations but, exceptionally, I can say that this incident occurred because the submarine did not correctly identify the Karen as a fishing vessel with nets in the water, and thus did not give her the berth she would otherwise have had.

'Moreover, had the submarine been aware of the incident at the time, which it was not, then the protocols in place under the code of practice for submarine operations in the vicinity of fishing vessels would have required the submarine to surface and remain on scene while the matter was investigated.'

Royal Navy subs must surface if they get entangled in fishing vessel nets.

Alarming episode: The Karen was towed at 10 knots during yesterday's incident and was badly damaged

The coastguard said The Karen reported a collision at a point known as the Calf of Man not far from the Isle of Man.

The four fishing crew members scrambled to release wires connecting the net to the out-of-control trawler, which had been moving slowly forward but was suddenly sent careering backwards through the water.

As the ship steadied, the shaken trawlermen stopped to catch their breath but there was no sign of the cause.

The vessel made its way back to Ardglass where part of the deck had to be lifted because it was so badly damaged, and another section was ripped off.

Shortly after the incident Ms Mordaunt said she was confident no British submarine was involved.

South Down MP Margaret Ritchie said: 'Fishermen must be confident that their vessels will not be damaged by submarine activity and where incidents do take place, the Government will own up to it immediately.

'It's important now that the owner and crew of the Karen are compensated for the damage done to their vessel and the time they have lost at sea as a result. I will continue to pursue this matter until we have reached a satisfactory resolution.'

The Karen was towed at 10 knots during the incident, 18 miles off south-eastern Northern Ireland

Captain Paul Murphy points at a tracking system which shows the boat's movements during the incident

Sinn Fein Stormont Assembly member Chris Hazzard said fishermen deserved to be able to work in an environment where they did not have to worry about submarines sinking their boats as fishing was already a dangerous occupation.

'The British Government and MoD must now explain their actions, if any disciplinary measures will be taken arising out of this incident and how it will avoid similar incidents in the future.'

In March a trawler captain claimed his boat was nearly dragged down by a Russian submarine while fishing off the Scottish coast.

Angus Macleod, 46, was fishing for haddock and skate when he became convinced that a hostile vessel was caught up below his boat Aquarius.

The submarine attempted to free itself, taking the 65ft vessel and his two-ton catch with it.