A suspected U.S. drone strike killed eight of German nationality in northwest Pakistan on Monday

(Reuters) - A suspected U.S. drone strike killed eight  of German nationality in northwest Pakistan on Monday, Pakistani intelligence officials said.

They died when two missiles from a suspected CIA pilotless aircraft struck a mosque in Mirali in North Waziristan, the officials added. The attack came a day after the United States and Britain warned of an increased risk of terrorist attacks in Europe. Western security officials said last week they believed a group in northern Pakistan were connected to a plot to stage attacks. The militants were members of a group called Jihad Islami, the Pakistani intelligence officials said without elaborating. There was no independent verification and militants often dismiss official reports of successful operations against them. "People were gathering at the mosque for prayers when a missile hit the building," Mohammad Alam, a resident of Mirali, told Reuters by telephone, describing Monday's drone strike. "The area has been cordoned off by militants and they are not allowing anyone there." The State Department warned American citizens to exercise caution if traveling in Europe. Britain raised the threat level to "high" from "general" for its citizens traveling to Germany and France.

Matthias Gebauer, the chief correspondent for German news magazine Der Spiegel, told Al Jazeera that while finding verified information on the attack had been difficult, news that German citizens may be among those killed in the strike "did not come as a big surprise"."Because we know that about a couple of dozen German Islamists went from Germany to the Pakistani tribal belt, especially to Mir Ali," Gebauer said.There are reports that al-Qaeda's leadership, increasingly restrained by missile strikes from US drones in northwest Pakistan, prizes such "home-grown" recruits as they have Western passports.Pakistan's northwest region is seen by the US as a training ground for fighters. It has been hit with 21 drone attacks in September alone, the highest number in a single month.Besides al-Qaeda fighters, the CIA has been trying to eliminate leaders of the Haqqani network, an Afghan Taliban faction operating out of North Waziristan.

U.S.-PAKISTAN TENSIONS

The immediate trigger for Sunday's travel alerts was intelligence about a plot against European targets reportedly originating with a group of individuals in mountainous northern Pakistan, some of them believed to be European citizens.One security official in Germany said last week word of the plot had probably originated from the interrogation of a German-Afghan suspect in Afghanistan.The suspect believed to be behind the intelligence was identified by media as Ahmed Sidiqi, a German of Afghan origin. German media said he came from Hamburg and had been held in the U.S. military prison of Bagram in Afghanistan since July.German counter-terrorism expert Guido Steinberg told Reuters Sidiqi was a member of a cell of militants from Hamburg that was believed to be a central component of the conspiracy.