Note: A previous version of this story had a misspelled word in the headline.

An alleged neo-Nazi has threatened to kidnap the young crown princess of Belgium, Elisabeth, prompting tighter armed security measures around the country’s royal family. A letter sent to the French-language newspaper La Derniere Heure made the threat because the writer blamed the 12-year-old princess’ father, King Philippe, who serves as head of state, for allowing too many immigrants and other foreigners into Belgium. "I'm going to abduct Princess Elizabeth. This is no joke," declared the letter, which was written in German, addressed to the king himself and arrived over the weekend. 

The paper said it immediately notified police as well as the royal palace. Britain’s Daily Telegraph reported that DNA tests performed on the letter have failed to yield any clues to the sender's identity. Nonetheless, police and anti-terrorism squads are taking no chances -- armed units have been deployed outside the princess’ school, the Sint-Jan Berchmanscollege in Brussels. "The investigation has taken different directions but I obviously cannot reveal those," said Alain Lefevre, the director of Belgium's anti-terrorist unit. "We will naturally take precautions as required. The case is now in the hands of a criminal prosecutor and forensic investigators are hard at work."

Philippe became king only this summer, upon the abdication of his father, Albert II. Philippe. He and his wife, Queen Mathilde, have four children, of which Elisabeth is the eldest -- meaning Elisabeth is destined to one day become the queen herself, as she is first in line of succession.

Le Derniere Heure did not print the entire letter but characterized the contents as "sickening, racist and neo-Nazi." The contents blamed immigrants for Belgium’s "difficult economic situation in our country." "He expresses his disgust in terms that we prefer not to reproduce. Maghrebis [North Africans], Turks and Muslims are covered by the letter," the newspaper noted, adding that it also included references to Nazi ideology and imagery as well as Satanism and referred to immigrants as "untermensch" -- a German term roughly meaning "sub-human" that the Third Reich applied to Jews, Roma (gypsies) and others.

European media sources reported that the anonymous letter-writer estimated that immigrants from North Africa and Turkey are costing the state some 30 billion euros annually through state welfare benefits and other expenditures. Addressing the king directly, the letter writer warned: "You and your government are doing nothing about this." Like virtually all European states, Belgium is suffering under high unemployment (8.9 percent as of September 2013) and strict austerity measures.

Of Belgium’s 11 million people, one-fourth are of foreign origin: Some 1.2 million are from other European nations, and another 1.356 million are from non-Western countries, principally North Africa and Turkey.

In September 2006, Belgian police arrested 19 members of a neo-Nazi group called "Blood and Honor" -- some of whom were members of the army -- who possessed arms and held military training camps.