An evangelical pastor has called fidget spinners "satanic", claiming children perform the "sign of the devil" with their hands when playing with the wildly popular toy.

Juan Mariano Avalos, of the Congregation of the First Christians in Paraguay, posted a sermon on Facebook warning against the toy. In the video, he explains that when when spun, the spinner, formed by circles that rotate quickly, configures the satanic symbol "666".

"This sign is satanic," the pastor says in the video, pointing to the shape made by his hands as he rotates the toy.

"When they play, they do not realize they are raising their fingers like horns or doing '666', clearly evoking the enemy," Juan Mariano told local media, adding he realized the "true message" when he saw his 7-year-old daughter "giving the devil's signal" with her hands while playing with the spinner.

The pastor also warned parents not to allow their children to handle the toy.

While some on Facebook supported the pastor and thanked him for his concern, most dismissed his sermon as "ridiculous".

Wrote Jose Soler: "You have to be careful when you drink a cup of coffee with your hand so that the devil won't come out and take it."

Added Gabby Sánchez wrote: "I can't believe what I just saw and heard. The Lord forgive him for what he says!"

"We're not laughing at God, we're laughing at the pastor," said another.

Fidget spinners - which are two or three pronged devices with a ball bearing in a circular pad in the center, which the user balances with their index finger and thumb before flicking with their free hand - were invented by American Catherine Hettinger in the mid 1990's, according to The Telegraph.

Despite the fact fidget spinners have been available for two decades, the product exploded in popularity in 2017, the outlet notes. The toys have been selling out at shops and online retailers around the world, and 49 of the top 50 best selling toys on Amazon.com are currently fidget spinners or cubes.

Today, the toy, which ranges in price from $2 to $20, is marketed as a stress reliever for children and adults who have problems with focus or fidgeting such as those who suffer from ADHD, autism and anxiety.

Others have warned fidget spinners are dangerous for different reasons, as there have been reports of fidget spinners containing dangerously high amounts of lead. Some schools in the United States, France, and England have banned fidget spinners, claiming the toy "just adds to the chaos".

"With the fidget spinner, you need to keep it going, they want to look at it spinning around... it is too distracting if you are trying to learn something new," Meredith Daly, a sixth-grade teacher at a public school outside Phoenix, Arizona, told the AP. "So we all decided 'No fidget spinners -- keep them in your backpacks!'"

Elizabeth Maughan, who teaches fifth and sixth graders in a school just outside Oklahoma City, told NPR: "When you have 10 or 15 in a room, it's just this whirring and it's an irresistible siren call for everyone else to turn around and look at whoever has it out, and [it's] completely distracting."

Fidget spinners first started trending on Google between January 29 and February 4 and peaked on May 6. However, data from Google searches and online sales show its popularity has since been on a rapid decline, Slice Intelligence reports.