A Hampshire museum has been accused of animal cruelty after setting up nets to trap a flock of 100 pigeons living inside one of its prize exhibits.
The pigeons are trapped behind the nets inside the hull
The birds are in HMS Alliance, a submarine from World War II which has been at the Royal Navy Submarine Museum in Gosport for 25 years.
The museum has set up nets to trap the birds before releasing them.
But the approach has angered some bird lovers who say the trapped pigeons are showing signs of distress.
The museum is planning a £4m project to conserve and repair the submarine, but that is being hampered by growing layers of corrosive pigeon droppings.
Last year, it attempted to solve the problem by shooting the pigeons, but that was unsuccessful.
A pest control company has now been brought in to put up nets over the bow and the stern, places where years of corrosion have left gaping holes.
Traps with food and water have also been set up to catch those birds inside the submarine.
The trapped pigeons are being given food and water
Once their entrance holes have been blocked, the birds will be shooed out of the hull.
Emma Haskell, from Pigeon Control Advisory Service, said in the meantime the birds were suffering.
"It's very distressing, she said.
"The birds are throwing themselves at the net and doing everything they can to get out."
Bob Mealings, curator at the Royal Navy Submarine Museum, said: "We are following the recommendations of the RSPCA and we are working with a licensed contractor who is working within guidelines laid down by the law."
The removal is expected to take several weeks and the trapped pigeons are being given food and water.