PRINCE CHARLES said the numbers of vulnerable young Muslims being radicalised by "crazy stuff" on the Internet was "frightening", in an interview to be broadcast Sunday.
The heir to the throne also voiced concern about Christians fleeing the Middle East in droves, saying the situation might end with very few left in the cradle of the religion.
In a BBC radio interview, Charles said radicalisation was "one of the greatest worries" and the issue could not be simply "swept under the carpet.
"It's the extent which this is happening is the alarming part," the 66-year-old said.
Speaking of "the values we hold dear", Charles said: "You'd think that the people who have come here, born here, go to school here would abide by those values and outlooks.
"But, the frightening part is that people can be so radicalised either through contact with somebody else or through the Internet and the extraordinary amount of crazy stuff which is on the Internet."
He added: "Some aspect of this radicalisation is a search for adventure and excitement at a particular age."
The Prince of Wales said much of his own work with young people in deprived areas had been aimed at finding "constructive paths" for people to channel their energies.
"There are some really interesting examples of how people can be de-radicalised once they become radicalised because I think sometimes they find they are horrified by what it leads to," he said.
He said more people now realised they had to address prevention.
"You can't just sweep it under the carpet."
Charles said the numbers of Christians in the Middle East was going "dramatically down", with people "intimidated to a degree you can't believe" where the Islamic State jihadist group has taken control in northern Iraq.
"There is a danger that there is going to be very, very few left," he said.
"Christians have been in the Middle East for 2,000 years. Before Islam came in the 8th century. And have contributed an enormous amount, as many Muslims and others would agree.
"So that makes it an even greater tragedy."
Charles is visiting Jordan, Kuwait, Saudi Arabia, Qatar and the United Arab Emirates from Saturday to Thursday.
As first in line to become the British monarch, Charles is thus next in the line of succession to become the supreme governor of the Church of England under the title Defender of the Faith.
He explained that he, as does his mother Queen Elizabeth II, interprets the role not as being "to defend Anglicism to the exclusion of other religions" but instead to protect all religions because "the Church has a duty to protect the free practice of all faiths in this country".
A new biography of Charles out Thursday has reignited debate about his suitability for the politically neutral role of king, given his outspoken views and energetic activism.