CHON BURI, Thailand (AP) — Bloody and battered, the Thai fighter from the red corner lost courage, turned from his opponent and flew out of the ring.

Behind until then, the Vietnamese winner from the blue corner was awarded a TKO and crowed victory — literally.

They were among 26 fighting cocks from 11 countries pitted against each other Sunday under a new set of rules the Thai organizers hope will promote a more humane style of the popular — if much-criticized — blood sport.

Losers will now be allowed to fight another day, rather than finish in a pot.

The rules were drafted by the Thai Native Chicken Conservation and Development Association for what was billed as the First International Amateur Cockfighting Competition, held before a packed arena on Thailand’s southeast coast and broadcast live on national television.

‘‘For several hundred years, these birds have been fighting each other to the death,’’ said Dhanin Chearavanont, president of Charoen Popkhand Group, one of the world’s largest poultry producers. ‘‘The association wants to change all that.’’

The C.P. Group, rivaled as an international poultry giant only by Tyson Foods Inc., financed the creation of the association two years ago to preserve the native chicken species, from which the aggressive fighting cocks are bred.

The cocks battled in classes ranging from strawweight — 6.38 pounds — to heavyweight at above 8.77 pounds.

Lethal metal spikes on the legs and razor blades on the wings have been forbidden. So were steroids, stimulants and depressants.

The match now ends if a cock runs away three consecutive times, is unable to keep a fighting stance, suffers a broken bone, loses sight in one eye, or bleeds continuously from a cut.

‘‘The idea is to reduce the cases of torture and maltreatment,’’ said Dr. Paiboon Brunarugsa, the veterinarian who drafted the rules. ‘‘But these cocks fight naturally, from the age of three months. At the age of eight months, they’re fighting their fathers.’’

Even with the new rules, cockfighting is still a rough sport. Although their natural spurs are covered with gloves, the birds instinctively leap at each other and slash each other’s chests, heads and backs with their powerful legs and beaks. Blinding is a constant risk. The back of each rooster is often featherless and gouged from repeated blows.

The match lasts five 15-minute rounds — and the judges don’t even start awarding points until the last two, after the birds exhaust their initial flurry of blows.

In the three-minute pauses, the trainers wet down their fighter’s feathers, shove tail plumes down their throats to clean out sputum, and suck on the coxcombs to lift off blood and make the bird more alert.

Gambling was banned — owners made money by auctioning their birds after a bout, earning up to $600 — but the sport is inseparable from gambling in Asian culture. Every one of Thailand’s 76 provinces has a legal, weekly cockfighting event.

Animal-rights activists dismissed attempts to clean up the sport.

‘‘If you did not have gambling, you would not have cockfighting,’’ said Roger Lohanon, head of the Thai Society for the Prevention of Cruelty to Animals. ‘‘We should be ashamed we still have cockfighting in this country. It’s like slavery — just because our ancestors did it doesn’t mean we should.’’

The association claims that raising indigenous chickens, which scratch for bugs and grains in farmyards, can help poor Thai farmers. Exports of fighting birds to other countries are a $2.7 million annual business.

Meat from non-fighters is more textured and flavorful, akin to the free-range chickens in North America.

Zhao Sha Fu, a Chinese fighting cock owner, said he would never eat a dead fighting bird because it would show disrespect to a 4,000-year-old breed.

‘‘In China, the cock is about strength,’’ Zhao said. ‘‘We bury our birds. They are like our friends.’’