YouTube says it is responding to particular concerns in the UK
YouTube is to ban footage showing weapons being used to intimidate people on its website in the UK.
The new policy was being introduced because of "particular concern" in Britain over the subject, the site's owners, Google, said.
MPs criticised video-sharing websites, including YouTube, in July, saying they should be doing more to vet content.
Home Secretary Jacqui Smith welcomed the YouTube ban and called on other internet sites to follow suit.
YouTube said the introduction of the new rule on weapons and intimidation would be the first time the site had made a policy change targeted specifically at the UK.
We recognise that there has been particular concern over videos in the UK that involve showing weapons with the aim of intimidation
Direct threatening of any groups or individuals has always been banned worldwide, but a spokesman for YouTube said it was necessary to reflect "local laws and sensitivities" in countries viewing the "diverse content posted by users" as the site's community evolved.
For instance, there are already some other country-specific rules, including a ban on Nazi-related footage in Germany.
The move comes amid growing concern about knife and gun crime among young people in the UK.
"We recognise that there has been particular concern over videos in the UK that involve showing weapons with the aim of intimidation, and this is one of the areas we are addressing," the spokesman said.
"We have just established a new policy in the UK to prohibit this kind of material, and with the help of our community we'll continue to work to keep YouTube as a platform for safe and lawful expression."
The spokesman said although the site was responding to concerns raised by the media and government over footage of weapons, the move was not a "paradigm shift" from existing policy.
Strict rules already existed to vet content and the change was just "tightening" those rules, he added.
I would like to see other internet service providers follow suit to reinforce our message that violence will not be tolerated either on the internet or in the real world
Home Secretary Jacqui Smith
The Home Secretary said she was "extremely pleased" YouTube had "taken action to ban videos glamourising weapons".
"This is a real step forward. I would like to see other internet service providers follow suit to reinforce our message that violence will not be tolerated either on the internet or in the real world," she added.
In July, the Culture, Media and Sport select committee called for a new industry body to be set up to protect children from harmful content on the web.
The committee also said it should be "standard practice" for sites hosting user-generated content to review material proactively.
While the committee recommended the creation of an industry body responsible for policing the web, it stopped short of making regulation mandatory.
At the time, YouTube said it was confident its system and the site's 24/7 review team dealt with all problem content swiftly.