Ministers have been accused of a "cover up" after sanctioning the slaughter of thousands of ducks.

Wildlife campaigners are furious that a "trial cull" of more than 2,600 ruddy ducks was carried out, due to breeding fears.

It's quite ludicrous to speak of any cover up

Defra spokesman

They say in previous trials the birds have taken hours to die and have been shot several times.

The results of the pilot cull - which took place in the West Midlands, Anglesey and Fife - are being examined by the Department for Environment, Food and Rural Affairs (Defra).

A spokesman for Defra denied there had been any cover-up, and said the cull had been conducted "as humanely as possible".

'Genetic cleansing'

Ruddy ducks were introduced into the UK from American in 1950 and there are now around 3,000 left in the country.

The birds have been flying to Spain where they breed with the endangered white-headed duck, creating a hybrid bird.

Wildlife group Animal Aid said the killing of thousands of birds, from 1999 to spring this year, was part of a "sick genetic cleansing operation".

Director Andrew Tyler said: "The whole scheme is callous, cynical and anti-democratic."

He said ruddy ducks scatter when they are under threat and have settled on around 1,000 sites.

He added: "A special licence to gain compulsory access to land would have to be sought ... reminiscent of foot and mouth."

A Defra spokesman said: "It's quite ludicrous to speak of any cover up of the trial cull of ruddy ducks in the UK."

'Humane cull'

He said the contract for the control of the ruddy ducks was awarded to the Central Science Laboratory, an agency of Defra.

"The field officers (who culled the birds) were recruited by advertising in the press," he added.

He said priority was given to ensuring all the birds were killed as quickly and humanely as possible.

The cull cost �90,000 over four financial years, he said.

It was organised after the Bern Standing Committee, a European body, approved an eradication strategy for the ruddy duck in Europe.

Defra is said to be considering the feasibility of a complete eradication of the birds from the UK.