[Excerpt:  "The Sydney-born Muhammad has gained notoriety for, among other things, calling on young children to be radicalized and blaming rape victims for their own attacks.

The paper posted an English-language audio clip in which he refers to Wilders as "this Satan, this devil, this politician in Holland" and explains that anyone who talks about Islam like Wilders does should be executed by beheading."]

Wilders' Freedom Party scored the biggest gains in June 9 polls and is currently negotiating to form a new minority government with the Liberals and Christian Democrats. Polls show Wilders would win a new election if one were called now.

Wilders demanded to know why he had learnt about the threat from the newspaper and not from Dutch authorities who are guarding him after a film and remarks he made angered Muslims around the world.

De Telegraaf, the Netherlands' largest newspaper, led its front page on Friday with a story on the speech by Feiz Muhammad.

The Sydney-born Muhammad has gained notoriety for, among other things, calling on young children to be radicalized and blaming rape victims for their own attacks.

The paper posted an English-language audio clip in which he refers to Wilders as "this Satan, this devil, this politician in Holland" and explains that anyone who talks about Islam like Wilders does should be executed by beheading.

De Telegraaf did not say when the speech was given but said it and the Dutch secret service both had copies. According to his website, Muhammad is based in Malaysia.

Wilders told Reuters it was "really terrible news" and that he was taking it seriously.

"I will ask for clarification from the Dutch minister of interior/justice why the secret service and anti-terrorism unit NCTb have not informed me before and what the consequences will be for me," he said in an email.

A spokesman for the Dutch secret service referred inquiries on the threat to the NCTb. A spokeswoman for the NCTb was not available to comment.

Wilders is currently on trial in the Netherlands for inciting hatred and discrimination against Muslims.

The Freedom Party leader made a film in 2008 which accused the Koran of inciting violence and mixed images of terrorist attacks with quotations from the Islamic holy book.

Wilders was also charged because of outspoken remarks in the media, such as an opinion piece in a Dutch daily in which he compared Islam to fascism and the Koran to Adolf Hitler's book "Mein Kampf."

Of late he has been in the news for plans to speak out against a planned mosque in New York City on September 11, the ninth anniversary of the attacks that killed nearly 3,000 people.

But his views have also made him extremely popular with a segment of the country uneasy about the Netherlands' commitment to multiculturalism.

(Reporting by Ben Berkowitz; Editing by Jon Hemming)