Mexico's "circus wars" are heating up, with a growing movement to ban circus animals meeting rising anger from circus workers.

There have been messages posted on social networking sites urging people to attack circuses, Armando Cedeno, the head of the nation's circus owners association, said at a demonstration by circus performers.

"We have a lot of threats on Facebook, with environmentalists urging people to go burn down circuses, which is very worrisome," Cedeno said as he oversaw a protest in Mexico City's main square at which circus entertainers put on a free show with horses and dogs — the only animals they will be allowed to use under a new city law banning acts with lions, tigers, elephants, and other "wild" animals.

Aguascalientes state legislator Gilberto Gutierrez, a member of Mexico's Green party, said violence has already been inflicted by the circus side. He said security guards beat him and other animal rights activists in front of a circus in his state in late June.

"They broke two of my teeth and it was a direct hit," Gutierrez said. "It was an attack by the circus people, by the security guards they employ."

The circus claimed the animal activists were blocking the entrance to the circus in Aguascalientes, where it is still legal to perform with exotic animals. Insults flew first, then fists and belts, the circus said.

Gutierrez acknowledged the demonstrators were posted in a narrow, four-foot strip of sidewalk at the entrance, but he insisted nobody was prevented from entering. At least two security personnel were detained in the case.

There have been mutual accusations of illegal acts, including a giraffe set loose to gallop through a suburb of the northern city of Monterrey. Video posted on social media sites showed surprised motorists making quick maneuvers to avoid the galloping giraffe outside the circus grounds, and the Barley Circus accused activists of opening the pen so the giraffe could escape.

Barley Circus spokesman Isaac Vertiz said: "The giraffe is always let outside in the morning, and the keeper went back inside for a moment to get food" for the giraffe. "In the meantime, within five minutes, somebody went in and opened the pen and let her out."

Vertiz said someone also spray-painted circus trailers and tried to break into circus vehicles. He said he suspects animal rights activists but conceded he has no proof.

Gutierrez denied animal activists have broken the law. "We will take this issue to its final consequences, without breaking the law," he said.

Animal rights activists say they are fighting the kind of abuses that came to light in March when environmental inspectors raided a small, provincial circus in the southern state of Yucatan and seized a black bear that had its lower jaw and upper teeth largely ripped out or cut off, apparently to keep it from biting.

On the other side, circus people say they are closely regulated and inspected, and they feel the Mexico City ban passed in June unfairly singles them out.

Mexico City and six of Mexico's 32 states have now banned circus animals. The circus-animal ban does not apply to shows with dolphins or bullfighting nor does it prohibit the use of animals in Mexico's traditional rodeos.