Led by minister Fred Phelps , the small group's hatred of the royal family and all things Swedish is linked directly to an equally virulent hatred of homosexuals.
Phelps praises homophobic crimes, including murder. When controversial Swedish minister Åke Green was convicted of inciting hatred of homosexuals following an anti-gay sermon, Phelps saw red and turned his attention to Sweden.
"You're doomed to spend eternity in hell," he said. "All you Swedes and your Swedish king and his family."
As part of the campaign Phelps launched the website God Hates Sweden , which attacks the royal family and delights in the loss of Swedish lives in the 2004 tsunami disaster.
Princess Madeleine has been the main recipient of the sect's abuse, Expressen reports.
"I know that this is happening all the time. There have been strange faxes containing all sorts of terms of abuse," court spokeswoman Nina Eldh told the newspaper.
The court's lawyers have so far failed in their attempts to call a halt to the site's anti-Swedish hate campaign.
Expressen's attempts to secure a comment from the group were met with resistance from an agitated female representative.
"We hate Sweden! Don't call here again," she said.