WASHINGTON — The US zoo association has issued tougher safety guidelines on elephants that include a requirement for all institutions to provide barriers that separate handlers from the animals.

The guidelines, believed to be among the most stringent in the world, won praise from animal rights activists, although the zoo association said that its primary concern was the working conditions of elephant handlers.

The Association of Zoos and Aquariums, which accredits 73 US zoos with elephants, concluded in a study that handlers are at greater risk the more time they spend in unrestricted space with the animals.

In a new policy, the association said it would require all zoos to provide barriers by September 2014 so that handlers would not generally be in direct contact with elephants, instead feeding them through bars or other restraints.

Zoos will have a grace period until 2016 if they cannot meet the guidelines but are making an effort. The policy still allows for direct contact with elephants if there is an explicit reason, such as medical treatment or breeding.

"While this is a policy aimed squarely at occupational safety, it does so in a way that is consistent with providing the highest level of elephant care and welfare," association president Jim Maddy said in a statement this week.

The association said it had no statistics on the number of workers injured by elephants, but accidents are periodically reported at zoos involving the animals that weigh thousands of pounds (kilograms).

In January, a zoo worker in Knoxville, Tennessee, who was in close proximity to an elephant died while trying to give a treat when she was struck by the pachyderm's head and trunk.

People for the Ethical Treatment of Animals hailed the association's new policy, estimating that about half of US zoos now favor direct handling of elephants that involve sharp bullhooked goads.

"They are kept through domination and fear," said Delcianna Winders, a director at the animal rights group.

So-called protected contact that avoids direct handling "will be a fundamentally different way of interacting with elephants and it will benefit elephants and humans alike," she said.

But she said that circuses and unaccredited zoos will continue to emphasize direct contact, meaning "there will still be a very large number of elephants who are being handled through fear and aggression, unfortunately."

Steve Feldman, a spokesman for the Association of Zoos and Aquariums, criticized the animal rights group's description of elephant treatment and said the new policy was decided primarily on the basis of worker safety.

"PETA has deliberately mischaracterized this policy for its own gain," he said. "That's an organization that doesn't have the credentials or the credibility to address elephant care issues and certainly not elephant safety issues."

He defended the use of goads, saying: "When an elephant goad is used properly by trained professionals, it does not cause harm and it's a valuable tool in managing animals."

The European Association of Zoos and Aquariums does not have a similar policy on elephant contact but more zoos on the continent are shifting away from direct contact, said Danny de Man, a manager at the Amsterdam-based association.

"It's a debate between zoo management needs on the one hand and safety on the other. And you see a trend also in our region toward more protected contact," he said.