Secretly-filmed footage taken at Hall Farm in Hingham, Norfolk, shows the birds being herded onto crates to be taken away for slaughter.

But some workers are seen picking ducks up by their necks and swinging them before throwing them back into the flock.

As well as sick and injured birds, we also discovered dead birds left to rot among the flock.

Those that had been removed were found decomposing in a skip instead of being safely put in bags to avoid contamination.

After viewing the footage, the RSPCA told Sky News the pictures were "absolutely shocking".

Waitrose said that the behaviour seen on the film is totally unacceptable and completely goes against the high welfare standards Waitrose expects of its farmers. Waitrose told Sky News it was "appalled" by the footage and had suspended the farm from its list of suppliers while it investigates.

"As soon as we saw it we suspended the supplier and sent in a vet to ensure the welfare of the ducks remaining on the farm.

"Following an immediate and detailed investigation, we have now ended our relationship with the supplier and they no longer supply Waitrose.

Farm animal welfare expert Dr Marc Cooper said: "Commercially reared meat ducks are flightless, heavy animals and handling them in this manner is likely to cause injury to their neck, legs and body.

"Throwing live ducks is incredibly inhumane and would most certainly have caused suffering through pain or injury to the birds.

"The footage shows unacceptable levels of lameness and injury in the flock. Birds that are ill or injured should receive veterinary attention or be humanely culled without delay.

"Dead birds in a state of decomposition that haven't been removed presents a risk of disease to the living birds and is indicative of a lack of even the most basic level of stockmanship duties."

Hall Farm is contracted by producer Green Label, who hired the workers.

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