Peter Dejong / AP

A ritually-slaughtered lamb is delivered at a halal butcher shop on the market in The Hague, Netherlands, Tuesday Dec. 13.

AMSTERDAM -- Political support for a proposed ban on slaughtering animals without stunning them first appeared to crumble Tuesday as the Dutch senate debated legislation that Muslim and Jewish groups say violates their religious rights.

The ban — proposed by an animal rights party and widely supported by Dutch voters — passed Parliament's lower house by a 116-30 margin in June, raising an international outcry from religious groups.

Although senators will not vote until Dec. 20, it appeared from Tuesday's debate that several parties that initially backed the ban in parliament — including the Netherlands' two largest — have changed their mind.

If the Netherlands does outlaw the slaughtering practices that make meat kosher for Jews or halal for Muslims, it will be the second country after New Zealand to do so in recent years. It would join Switzerland, the Scandinavian and Baltic countries, whose bans are mostly traceable to pre-World War II anti-Semitism.

Speaking first, Labor senator Nico Schrijver said his party now has "many questions" about the bill, including asking why it "so specifically aims its arrows at the rather small number of ritual slaughterers and why not large-scale industrial slaughter, which involves 500 million animals per year?"

"It seems to me that there may be much more effective, and less far-reaching methods that achieve the same goal" of improving animal welfare, Schrijver said, citing better education for slaughterers and better conditions in slaughterhouses.

Muslims, mostly immigrants from Turkey and Morocco, represent about a million of the 16 million Dutch population. The once-strong Jewish community numbers around 50,000 after most were deported and killed by the Nazis during World War II.

In both religions, tradition prescribes that animals' throats be cut swiftly with a razor-sharp knife while they are still conscious, so that they bleed to death quickly.

Support for the ban comes both from left-leaning voters who see this technique as inhumane, and from social conservatives who see it as foreign and barbaric.

Outside the debate, Esther Ouwehand of the tiny Party for the Animals, which proposed the ban, said it was unjust to inflict "extra suffering on animals to satisfy religious opinion."

The ban's most influential backer has been the Netherlands' anti-Islam Freedom Party.

"Do we want such practices in a civilized country as ours?" asked Freedom senator Marjolein Faber, after describing a worst-case scenario of a panicked animal taking six minutes to lose consciousness after a botched ritual slaughter.

The Royal Dutch Veterinary Association says it believes slaughtering cattle in particular while still conscious inflicts unnecessary suffering.

But Moshe Kantor, President of the European Jewish Congress, said there is "no scientific evidence" that religious slaughter, performed properly, is more painful for animals than stunning.

He said the law should be voted down in the name of freedom of religion.

"If this law is passed in a country known for its tolerant and open society, it could result in a very dangerous domino effect that could spread to other parts of Europe," he said.

Among the two parties in the Netherlands' governing coalition, the Christian Democrats opposed the ban from the beginning out of concern for the rights of religious minorities.

The pro-business VVD party, the country's largest, also now appears unlikely to support the ban.

VVD senator Sybe Schaap slammed the bill for "ethical absolutism" and said offering incentives for slaughterhouses to improve their practices would have a more positive effect than a ban.

The Dutch undersecretary for Economic Affairs Henk Blekers has said the Cabinet will only take a position on the bill after the Senate vote.