视频播放位置 下载安装Flash播放器

British Home Secretary Theresa May on Friday announced that the Britain's Joint Terrorism Analysis Centre (JTAC) has changed the country's threat level from international terrorism from "substantial" to "severe."

This means a terrorist attack is highly likely, although there is no intelligence to suggest that one is imminent, according to a Home Office statement.

"The increase in the threat level is related to developments in Syria and Iraq where terrorist groups are planning attacks against the West. Some of these plots are likely to involve foreign fighters who have traveled there from the UK and Europe to take part in those conflicts," the statement quoted May as saying.

"We face a real and serious threat in the UK from international terrorism. I would urge the public to remain vigilant and to report any suspicious activity to the police," she added.

Commenting on the Islamic State's threat to the country, British Prime Minister David Cameron said: "We cannot appease this ideology. We have to confront it at home and abroad."

"It's by insisting on British values that we will defeat extremism, protect our way of life and keep all our people safe," the prime minister said on his twitter feed, following the raising of the threat level.

Britain's official threat level informs security professionals across the public and private sectors as they make decisions about the appropriate level of protection in place across the country.

The Home Office said JTAC's judgements are made on the basis of the latest intelligence and are independent of Ministers.

"We have already taken steps to amend our powers and increase our capabilities for dealing with the developing terrorist threats we face. That process will continue and the British public should be in no doubt that we will take the strongest possible action to protect our national security," May noted.

The Home Office said the public should always remain alert to the danger of terrorism, look out for suspicious bags on public transport or any other potential signs of terrorist activity.

However, it revealed that the risk of being caught up in a terrorist attack is very low, and the public "should not let the fear of terrorism stop them from going about their day-to-day life as normal."