"Currently we have no information but we are investigating," a spokeswoman for the foreign ministry in Berlin told AFP.
The missile attack took late on Monday in the North Waziristan tribal district bordering Afghanistan, a purported hideout for foreign and homegrown militants linked to the Taliban and Al-Qaeda.
"Five German rebels of Turkish origin and three local militants were killed in the strike," a Pakistani security official said.
The strike came hours after Japan and Sweden joined Washington and London in issuing an alert warning of the "possible terrorist attack" by Al-Qaeda and affiliated groups against their citizens travelling in Europe.
This followed reports in British and US media said that an Al-Qaeda plot to carry out attacks in Britain, France and Germany, similar to the siege in Mumbai in 2008 that killed 166 people, had been uncovered.
The source of the threat information was a German citizen of Afghan descent captured on his way to Europe and now being held in Afghanistan, the reports said.
According to the Federal Office for the Protection of the Constitution's annual report in June, there are 29 Islamic extremist organisations in Germany, with 36,000 members at the end of 2009 -- 1,500 more than the year before.
Some 200 Germans or foreigners living in Germany have spent time in Pakistan with the intention of receiving paramilitary training from Islamist groups, the agency said.
Konrad Freiberg, the head of police union GdP, said on Tuesday that there were more than 100 "dangerous Islamists" in Germany.
"Close to 40 men, who have undergone explosives training in camps abroad, are back living in Germany," Freiberg told the Passauer Neue Presse daily.
Germany, which opposed the 2003 US-led invasion of Iraq but has more than 4,750 troops in Afghanistan under NATO command, has beefed up security and surveillance in response to the threat of Islamic militant attacks.
Germany's interior minister said that Berlin was well aware that the country was in the sights of "terrorists" but that there were no "concrete" indications of an attack, warning against what he called "alarmism."
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