LONDON – These days, teenagers need only wear a hooded sweatshirt to send shivers of fear through the heart of middle-class Britons.

Young people wearing “hoodies” have become a symbol of low-level vandalism and petty crime. Since last month, about half a dozen shopping malls and schools in Britain have banned hoods and other clothing that can hide one’s face.

Prime Minister Blair, as part of a larger effort to create what he calls a culture of respect, endorsed the clothing ban that began last month at the Bluewater Mall in the southeastern city of Kent.

“People are rightly fed up with street-corner and shopping-center thugs,” Mr. Blair said at a news conference. Such misbehaving, he added, “makes our town centers no-go areas for respectable citizens.”

Bluewater’s ban and Mr. Blair’s endorsement of it have ignited a public debate about personal freedom, preventing intimidation and the place of youth in society.

“It’s as if the streets and the malls are to be swept clean of anybody who might give you a little bit of difficulty,” said the chief executive of the government’s National Youth Agency, Tom Wylie, who has been critical of the focus on hoodies.

Some have noted the garments keep wearers warm and dry – something not to be dismissed in Britain’s climate. And some have complained that young people were being stereotyped.

For about a decade, the hooded sweatshirt has been perceived by some as intimidating. Some malls and schools have implemented informal bans on hoodies for years. But only recently have national politicians begun talking about the garments as a criminal threat, used by young thugs to conceal their identities from security cameras.

With Mr. Blair having launched his social campaign, hoodies are no longer being tolerated in many places. Last month, a court barred a Manchester teenager convicted of delinquent behavior from wearing a hoodie for five years.

After the widely publicized Bluewater ban, the Elephant & Castle Shopping Center in south London and several schools followed suit. Other malls announced that they were already enforcing informal bans.

At Elephant & Castle, vendors had been complaining that hooded teenagers intimidated customers and discouraged people from shopping, center manager Mark Knell said. Then, hooded teenagers broke four windows in six weeks. Security cameras caught the vandals on tape, but not their faces.

“It was really the last straw,” Mr. Knell said.

Now that the ban is in place, “you’re not on guard all the time,” Pat Mould, 73, said, sitting on a bench at the Elephant & Castle center while his wife shopped for groceries.

A mall security guard, Andre Klem, 24, said he enforced the ban every day and was happy to do it. “When they’ve got their hoods on, they’re like robbers,” Mr. Klem said. Teenage boys would run around, playing like they were American gangster rappers, he said. But when the teenagers take their hoods off, they go back to being “normal kids,” Mr. Klem said.

Two 16-year-old shoppers, dressed in baggy sweat-suits with hooded tops and baseball caps turned backward, agreed that the ban was a good idea. They said they wore their hoods in the street for style. But inside, they kept their hoods down, “so people don’t start looking at you in a way that you don’t want them to.”

“I haven’t worn a hoodie for about eight years, because of the stigma that goes with it,” said George Maiga, 24, who works in central London at the Gap, which sells hooded sweatshirts.

Civil libertarians, however, have expressed reservations about linking style to behavior.

“You are once again creating this fear of this younger generation who are up to no good right across the board, rather than actually targeting individuals who are engaged in criminal activity,” the campaign coordinator for the civil rights group Liberty, Doug Jewell, said.