Three former circus tigers will arrive at a sanctuary in Florida on Monday, at the conclusion of a harrowing 18-month recovery operation that saw their rescuers exposed to repeated intimidation and threats from an armed Guatemalan mob.

Workers for the California-based Animal Defenders International say they endured the harassment after rescuing six lions and 15 tigers from circuses in the Central American country following a 2017 law banning live performances by animals.

In one of the worst incidents, they said an armed group invaded a transitional rescue center the charity had set up on private land designated by the government, stealing fences, gates and workers’ possessions and attempting to take the animals back.

The ADI team said it locked itself inside the facility until police and government officials arrived, then hastened efforts to relocate all the animals to a more secure temporary rescue center closer to Guatemala City’s La Aurora airport in September, protected by its own armed guards.

“It was very unnerving and fractious,” said Tim Phillips, the group’s vice-president, who believes the landowner was trying to cash in on the enforced presence of the animals on his property. “We’ve rescued more than 150 animals in Bolivia, Peru and Colombia and never come across this kind of behavior.

“The reptile park we were allocated to seemed to have its eyes on milking US charities and donors for funds and effectively setting up a mini-zoo. Later, they were openly campaigning with the circuses who were trying to disrupt the rescue and overturn the ban.

“We find that once we show an interest in the animals the perception is that there must be lots of money to be made. Also, these animals are worth more dead than alive, for their bones, teeth and skins, or to be sold as pets. Internationally, animal trafficking is behind only drugs, arms and human trafficking.”

On Monday, three male tigers – Kimba, aged two and a half, and nine-year-olds Max and Simba – will be airlifted to Miami and taken by road to Big Cat Rescue, a 67-acre preserve in Tampa that houses more than 60 exotic animals. The remaining lions and tigers are being prepared to fly to ADI’s recently opened 455-acre grassland sanctuary in South Africa before Christmas.

Phillips said getting some of the circuses to release the animals had also been an ordeal, despite the support of the Guatemalan government, army and animal welfare division.

One circus, he said, surrendered nine tigers and two lions but retained six tigers the group eventually rescued from a circus wagon parked in a scrapyard. During the original handover, Phillips said the ADI team was harassed by circus workers who stole their tools, while one circus employee tried to distract them by exposing himself.

On another occasion, rescuers had to stop a circus worker beating a tiger with a metal bar as he was trying to move the animal between cages.

“The tiger had been in a cage all his life, he was terrified,” Phillips said. “This circus guy comes up and goes mad, shouting at the tiger, lashing out and hitting it with the bar, leaving it with a bleeding leg and mouth. It could have been worse but it highlighted the brutality in these places.”

Once rescued, the animals received specialized veterinary care.

“Two tigers we rescued had seizures, they’re so incredibly inbred,” Phillips said. “Three of the animals needed dental surgery.”

Guatemala is among the most recent countries to adopt laws banning live animals in circus performances, according to ADI, which lists 46 countries and 32 of the 50 states of the US with prohibitions.

In October, California’s governor, Gavin Newsom, signed a bill banning most animals from circus performances while also making it the first state to outlaw the manufacture and sale of new fur products.

In May, Arizona congressmen Raúl Grijalva and David Schweikert introduced a bill for the traveling exotic animal and public safety protection act, which would impose the first federal restrictions on the use of wild animals and update what Grijalva sees as “antiquated” animal welfare laws.

The bill is endorsed by numerous animal advocacy groups including ADI.