The US State Department has issued an alert, warning citizens "to the potential for terrorist attacks in Europe." The Department did not specify a country, issuing the updated guidance for the whole of Europe.

The alert, published on the State Department's website, said that "current information suggests" al-Qaeda and affiliated groups were continuing to plan commando-style attacks, similar to the 2008 atrocities in Mumbai.

Separately, the British foreign ministry on Sunday updated its advice for citizens traveling to France and Germany, warning there was a "high threat" of terrorism in the two European countries.

Public spaces could be potential targets

American citizens have been warned that public places could be potential targets and that they should "take every precaution to be aware of surroundings." Potential targets could be railways and subways and other tourist places, according to the US State Department.

"Terrorists have targeted and attacked subway and rail systems, as well as aviation and maritime services," the alert said.

It comes as media in the past week reported that intelligence agencies in Germany, France, the UK and the US foiled an attempted strike on a series of European cities.

As a result the UK has also updated its travel advice for France and Germany, warning there was a "high threat" of terrorism.

British Home Secretary Theresa May said on Sunday the US advice was "consistent" with London's own assessment of the threat.

"As we have consistently made clear, we face a real and serious threat from terrorism," she said.

"We work closely with our international partners in countering terrorism and the US advice is consistent with our assessment," she said.

The alert – which the State Department issues regarding specific events – is one step down from a travel warning. A total of 31 travel warnings are in effect for various countries including Afghanistan, Iraq, Israel, Sudan and Somalia.

Author: Catherine Bolsover (Reuters, AFP)

Editor: Sonia Phalnikar