An RSPCA spokesman said they had no choice following what they believed was unnecessary and irresponsible action by the farmers.

The animal welfare charity said it had no choice about putting the animals down as they were not tagged.

This made it impossible to trace their histories to check if they were from BSE-free herds and the RSPCA was informed it was illegal either to keep them or to move them.

RSPCA officer Huw Evans said: "By law, we are not allowed to move them because we cannot prove that they do not have BSE and may contaminate other animals.

"We would love to have homes found for them but we are not allowed to."

RSPCA spokesman Huw Evans dubbed the action 'a reckless publicity stunt'

The RSPCA has warned that if it finds the farmers responsible for abandoning the animals, they will be prosecuted. It has condemned the dumping as a "reckless publicity stunt".

The calves' destruction came the day after Welsh Agriculture Secretary Christine Gwyther met her Westminster counterpart to press for the extension of a vital calf compensation scheme for farmers.

But Agriculture Minister Nick Brown offered no extra cash to Welsh beef farmers and Ms Gwyther is now expected to raise the matter in a meeting next week with Assembly First Secretary Alun Michael.

The cattle industry in Wales has been in crisis since the government scrapped a scheme which guaranteed farmers a minimum price for bull calves, which could not be sold abroad due to the beef export ban.

BBC Wales's Sian Parry-Hughes speaks to MEP Robert Sturdy

MEP Robert Sturdy, Conservative agriculture spokesman in Europe, said it was "about time" questions were asked about the future of the British farming industry.

"If we do want it, we have to pay for it," he said.

The plight of farmers had been made difficult by shifts right across the livestock market.

"There is no doubt, whenever you interfere with a market, farmers move. The trouble for livestock farmers is that they have very little room to manoeuvre."

Many Welsh farmers have found it impossible to sell their calves since the collapse of the export trade.

A total of 17 were dumped in public places in order to draw attention to the industry's plight.

The BBC's Wyre Davies reports: "It costs more to process them through market than they're worth"

On Wednesday, the Farmers' Union of Wales, the National Farmers' Union and the Country Landowners' Association met Ms Gwyther to call for emergency discussions between farming organisations and government throughout the UK.

Ms Gwyther pledged to support farmers in the battle to restore the compensation scheme for bull calves.

"I have assured farmers' leaders that I will be giving further thought to their suggestions," said Ms Gwyther.

"In principle, I support these ideas, but there are financial and legal problems that would have to be overcome before they could be brought in.

Christine Gwyther held talks with farmers' leaders

"Early next week, I will be meeting First Secretary Alun Michael and it would not be sensible to make any decisions on today's proposals before then."

However, Bob Parry, leader of the FUW, said after the meeting that dealing with the Assembly was useless and that farmers needed to go to a higher level of government.

BBC Wales's Jon Manel joins the RSPCA in rescuing an abandoned calf

Farmers want the veal trade to the continent to reopen or the £40-per-calf compensation scheme to be reintroduced.

Bull calves sold for as little as 50 pence each at Cardigan mart in west Wales on Monday.