A senior vet has spoken out against the "unacceptable" rise in the number of farm animals slaughtered by having their throats cut while fully conscious.

The practice is allowed under UK and EU law to satisfy the dietary requirements of Jews and Muslims.

But there is evidence that far more animals are being killed this way than is necessary for religious reasons alone, according to Professor Bill Reilly, a former president of the British Veterinary Association (BVA).

Writing in the Veterinary Record, he calls for action to curb, if not halt, the slaughter of animals for meat consumption without prior stunning.

He also suggests that some abattoirs might be refusing to stun animals before slaughter simply to cut costs.

Although legislation permits Schecita (Jewish) or Halal (Muslim) "non-stun" slaughter, it states that this must not cause "unnecessary suffering".

But Reilly insists the animals suffer a great deal.

As a postgraduate veterinary student in the 1970s he was "appalled" to witness Schecita slaughter for the first time, he said. "The distress, fear and pain were there for all to see (and hear) in the abattoir."

The former Farm Animal Welfare Council (FAWC) had concluded that throat-cutting resulted in "very significant pain and distress", Reilly said.

A report from the EU-funded Dialrel Project, which promotes international dialogue on issues of religious slaughter, came to a similar view, based on the fact that the throat was rich in nerve endings.

Reilly said an estimated two million animals, mostly poultry, were killed in the UK each year without stunning for the orthodox Jewish community.

Halal meat now accounted for a quarter of the entire UK meat market, Reilly added. Anecdotal evidence suggested that almost half of lambs destined for slaughter were killed without prior stunning.

Yet the Muslim community represented only 3% to 4% of the UK population, Reilly said.

Much of the meat from non-stunned animals was likely to end up on the secular market, she added.

A spokesman for the Food Standards Agency (FSA) said the number of animals not stunned prior to slaughter was relatively low, accounting for 3% of cattle, 10% of sheep and goats, and 4% of poultry.