BIRD flu is believed to have killed a dozen swans and geese found dead in the Grand Union Canal.

The majority of the waterfowl carcasses were spotted close to Browning’s Island in Little Venice. Experts have not confirmed what is behind the tragic scenes reported by tourist waterboat operators.

It comes as official government agencies warn of “the biggest ever outbreak of bird flu in Great Britain”.

Some pelicans have already been moved out of St James’s Park with the long-beaked water birds susceptible to the spread of avian flu.

Ben Perkins, who helps run river tours for the London Waterbus Company, said in recent weeks he had seen “lots of swans and geese dead lately around the canal at Little Venice”, adding that he was particularly ­“concerned for the avian population” on Robert Browning’s Island.

The small islet is named after the Victorian poet who lived nearby in Maida Vale.

Mr Perkins later told the Local Democracy Reporting Service: “Usually you see some dead birds every few months but we have seen 10 or 12 in the last few weeks. If you come with us on a day trip you may see three or four dead birds and carcasses in the water.”

Despite geese culls taking place in Norfolk, Suffolk and Essex, 40 dead swans were found this week in Sudbury, while many others were spotted in Lincolnshire.

Every year during the winter months migrating birds return with avian flu, potentially infecting wild birds that they come into contact with.

This can cause clusters of dead birds, especially waterfowl like ducks and geese, who are more likely to catch it via contaminated water. The virus spreads from bird to bird by direct contact, contaminated body fluids and faeces, and contaminated feed or dirty water.

The Canal and River Trust said: “We’re aware of reports of dead swans in the Little Venice area (some of which may be duplicate reports). The Department for Environment, Food and Rural Affairs (Defra) is responsible for investigating potential avian flu cases.”

It said that bird flu occurs naturally among wild aquatic birds such as ducks, geese and swans across the world.

“If you find dead wild waterfowl (swans, geese or ducks) or other dead wild birds, such as gulls or birds of prey, you should report them to the Defra helpline on 03459 33 55 77.

“Do not touch or pick up any dead or visibly sick birds that you find.”

The Royal Parks said earlier this year pelicans had been moved out of St James’s Park as a “precaution” due the avian flu outbreak.

Call the Defra helpline if you find: one or more dead bird of prey or owl; three or more dead gulls or wild waterfowl (swans, geese and ducks); or five or more dead birds of any species.