SAN JUAN (REUTERS) - An attempt by the United States Congress to ban cockfighting in Puerto Rico has set off a debate about animal cruelty, put thousands of jobs at risk and sparked a possible power struggle between the US territory's government and Washington.

The 500-year-old tradition of cockfighting in Puerto Rico was due to end on Friday (Dec 20) under a law passed by Congress last year to bring the island in step with the prohibition in every US state.

But Puerto Rico Governor Wanda Vazquez on Wednesday signed legislation designed to allow cockfighting to continue. That could set up a conflict with US federal authorities.

Puerto Rican fans see cockfighting as part of their cultural heritage and say 27,000 jobs could be lost among breeders, food suppliers and others if the ban goes ahead.

They bristle at being ordered to end fights by Congress, where the island's three million people have no elected voting representative.

"This is an abuse the US government is committing against our culture," said fighting cock owner Carlos Junior Aponte Silva.

Animal rights groups say cockfighting is cruel.

The birds have spikes attached to their legs by owners to cause more damage to opponents as men gather around a pit to watch the combatants peck and scratch each other in 12-minute fights. The death of cocks during a bout or shortly afterward is common.

The cocks' lives are miserable even without fighting, says the People for the Ethical Treatment of Animals (Peta) group.

"Many of these birds spend most of their lives tethered by one leg near whatever object is intended to serve as their shelter, such as an overturned plastic barrel or a small wire cage placed directly on the ground," Peta says on its website.

With Puerto Rico's economy suffering from a debt crisis and the effects of devastating hurricanes in 2017, breeders say they are prepared to go underground if need be.

"If there's nothing before (December) 21st, well then we'll continue fighting cocks... we will become criminals," said part-time breeder Elvin Lugo.

While it is not clear how the issue will be resolved, the legislation signed by Ms Vazquez also urges negotiations between Puerto Rico and Congress for a five-year moratorium on the ban. It also prohibits the trade of fighting cocks between the island and the rest of the US to ensure there would be no breach of interstate commerce laws if cockfighting continued.