LONDON // Japan and Sweden joined the US and Britain yesterday in warning citizens about travelling in Europe because of concerns about a terror attack.
Pakistani intelligence officials, meanwhile, said five German militants were believed killed in an American missile strike close to the Afghan border.
Two officials said the victims were believed to be German citizens in the region for terrorist training. A third said they were believed to be foreigners, but gave no details.
The officials spoke anonymously because their agency does not permit operatives to be named in the media.
The travel advisories from Tokyo and Stockholm came as European authorities sought to calibrate their messages on counterterrorism efforts, hoping to raise public awareness about the threat but without sowing panic.
The warnings might damage Europe's lucrative tourism business at a time when the continent's economy has been coping with recession - though many tourists took the warnings in stride.
On Sunday, the US State Department urged Americans to be vigilant when visiting Europe, highlighting the "potential for terrorists to attack public transportation systems and other tourist infrastructure".
The UK Foreign Office then upgraded its advice to British tourists, warning them that there was a "high threat" of attacks in France and Germany.
Intelligence reports said teams of jihadists planned to seize and murder western hostages, similar to the attacks two years ago in Mumbai in which 10 gunmen killed 166 people and injured more than 300.
Last week, a Pakistani intelligence official said eight Germans and two British brothers were at the heart of the plot, but the plan was still in its early stages, with the suspects calling acquaintances in Europe to plan logistics.
Japan's alert warns its citizens in Europe to be especially cautious at the sites of possible attacks, such as public transport systems, tourist attractions and government facilities.
Germany's interior minister said yesterday no one needs to be alarmed. "We take all leads seriously and investigate them with high intensity," Thomas de Maizière told reporters. "But there is no need to be alarmist."
The plan to carry out attacks was reported to be only in the planning stage and there has been no visible increase in security, except in Paris where there have been several hoax threats of bombs planted at the Eiffel Tower.
The latest travel alert came as media reports yesterday provided details of the plot. The possible attacks were revealed by a German citizen of Afghan origin who was detained in Kabul in July as he tried to fly back to Europe after a year of alleged training in Pakistan.
Ahmed Sidiqi was part of a group planning attacks similar to the one in India, according to a report yesterday in the online edition of Der Spiegel magazine.
Mr Sidiqi told interrogators Osama bin Laden approved the plans and had also provided financing, according to Spiegel Online. On Sunday, Fox News in the United States, citing unnamed intelligence officials, reported that "a German-Pakistani national interrogated at Bagram air base" said militants had a list of targets, including the Eiffel Tower and Notre Dame Cathedral in Paris, Berlin's Brandenburg Gate, and central railway station and the Alexanderplatz TV tower.
German intelligence officials have also confirmed that Mr Sidiqi prayed at the same Hamburg mosque as Mohammad Atta, who commandeered the first airliner that crashed into New York's World Trade Center on 9/11.
Spiegel Online said the German interior ministry had confirmed that Mr Sidiqi, 36, who is of Afghan origin, left Germany in March 2009, and joined militant groups in the Afghan-Pakistan border area. Other young Muslims from Germany and Britain are still believed to be in the camps.
Mr Sidiqi, who worked as a cleaner at Hamburg airport until leaving for Pakistan last year, was reported to have met Sheikh Younis al Mauretani, the No 3 in the al Qa'eda hierarchy, early this summer in Mir Ali in Pakistan.
They discussed possible attacks in several European countries, including France and Britain, Spiegel Online reported. He is said to have told interrogators he had fought in Afghanistan and had met Said Bahaji, one of the men who provided support for the terrorists involved in the 9/11 attacks.
US tourists at the Eiffel Tower and other attractions across Europe were alert yesterday. "We decided not to go up the Eiffel Tower because of the possibility of what could happen" after hearing the travel advisory, said Eileen Carbrello, 60, from Virginia. Several US visitors said they were used to living with the threat.
"You can only be a terrorist if people are terrified, and I refuse to be terrified," said Renee Lavine, 50, from Fort Worth, Texas, at London's top tourist draw, the British Museum.
Another key European tourist draw is Italy, where the interior minister, Roberto Maroni, said yesterday the threat level remained "high" but that no specific targets had been identified.
"The terrorist alert has never been underestimated," he said on Canale 5 television network. The leak by officials in Washington last week infuriated European security agencies, who already had several suspects under surveillance.
"The plans for an attack were at a very early stage and the hope had been that we could have arrested the suspects at a more advanced stage, when we had sufficient forensic evidence to charge them," a British security source said in an interview. "Unfortunately, the leak ruined those hopes."
* With additional reporting by the Associated Press, Agence France-Presse and Dow Jones