More nations issue warnings over Europe terror plot

The Eiffel Tower was evacuated twice in September

More governments have joined the US and UK in issuing travel warnings to their citizens about travelling in Europe, amid fears that al-Qaeda plans to attack cities on the continent.

Sweden and Japan urged their nationals to be vigilant when using public transport or visiting tourist sites.

Security sources warned last week of potential plots on the scale of the Mumbai attacks in 2008.

US authorities have cited France, Germany and the UK as possible targets.

The US state department said on Sunday that a "variety of means and weapons" might be used against official and private interests.

The British Foreign Office said that there was a "high threat" of attack in France and Germany, but said the current threat level in the UK would remain at severe.

'High abstract danger'

At a news conference in Berlin, German Interior Minister Thomas de Maiziere said there was no concrete evidence of an imminent attack and "no reason to be alarmist at this time".

He said Berlin had been aware of the possible al-Qaeda plot reported in recent weeks since early of 2009, and that security forces were vigilant because of a continuing "high abstract danger".

French officials, who raised their terror alert status to the second most serious "reinforced red" level last month, said there was no reason to raise it to the highest level, scarlet.

In recent weeks, the Eiffel Tower in Paris has twice been evacuated because of bomb threats.

Police say a man has been arrested south-west of the city on suspicion of issuing the threats.

In Italy, Interior Minister Roberto Maroni said the threat level remained high and security forces were watching the situation closely.