Fears of a terrorist attack in Europe were heightened today after
travel alerts were issued by both Washington and London, with the US
state department warning that public transport systems and tourist
attractions could be targeted, and Britain increasing the threat level
for travel to Germany and France.

The US alert made no mention of a specific European country, but pointed the finger at al-Qaida and its affiliates and suggested both official and private targets could be in terrorists' sights.

The move follows speculation that al-Qaida was planning a "commando-style" attack similar to the 2008 Mumbai massacre, in which 166 people were killed.

The
Foreign Office listed both France and Germany as facing a high threat
of terrorism, raising its previous classification of a general threat.
It said attacks could target places frequented by tourists.

However, well-placed British sources described intelligence about potential commando-style attacks as "ill-defined".

In
a separate move, the home secretary, Theresa May, said the threat level
for Britain had not changed, remaining severe, meaning an attack is
"highly likely". She said the UK and US were in agreement as to what was
going on. "I would urge the public to report suspicious activity to the
police in support of the efforts of our security services to discover,
track and disrupt terrorist activity," she said.

The revised
warnings come amid signs of growing jitters across Europe about planned
attacks. In Paris, the Eiffel Tower has been closed twice in two weeks,
the last time on Tuesday when a bomb warning was called in from a
telephone booth. The building was searched, but nothing was found.
Sweden also increased its threat level on Friday.

But Germany said
today it was not changing its risk assessment as there are "still no
concrete indications of imminent attacks" – despite a CNN report that
thousands of US troops stationed at the Ramstein Air Base were ordered
to stay in their homes on Friday night due to rising concerns about a
possible attack.

European officials said there was no intelligence
suggesting an attack was imminent, and warned against linking recent US
attacks on suspected militant bases in Pakistan with suggestions of
"commando-style" attacks in Europe. The attacks were directed against militants
in Waziristan, the Pakistani tribal area that borders Afghanistan. US
officials have been reported as saying that Osama bin Laden and his
inner circle may have been involved in co-ordinating plans for a number
of attacks on European cities, timed to occur simultaneously.

An
intelligence official in Pakistan has been reported as saying that two
British brothers, one of whom was killed in drone attacks, along with
eight Germans, were involved in the planning.

The New York Times said that information about the plot
had been acquired by intelligence agencies in part by interrogating
Ahmed Sidiqi, 36, a German of Afghan origin who had travelled from
Hamburg to Waziristan to receive arms and explosives training at a
militant camp. Sidiqi was reported to have been captured in Afghanistan
in July.

Though couched in cautious terms, the US travel alert is
unusually specific in its reference to danger spots. It mentions public
transport and tourist venues, reminding US travellers that terrorists
have targeted "subway and rail systems, as well as aviation and maritime
services".

European capitals are understood to have made no
efforts to dissuade the US from issuing the travel alert, suggesting
broad concurrence.

In recent years anti-terrorist operations
across Europe, backed by intelligence sharing with the US, have been
successful in preventing another atrocity. The last large-scale attack
in Europe was the London suicide bombings of July 2005 in which 52
people were killed.