According to Reuters news service, Taliban spokesman Qari Mohammad Yousuf said that four kidnapped foreigners had been executed after Taliban leader Mullah Mohammad Omar had ordered their deaths. According to Yousuf, their bodies were dumped in the Kandahar-Helmand areas in the southern part of the country.

"These people have come to Afghanistan on behest of America, hence they should be sentenced to death," Yousuf had said in an earlier statement. The hostages had been identified as three Albanians and one German by the Taliban.

But officials at Düsseldorf-based Ecolog services company, where the men had been working, said that the four employees missing since Saturday were all Albanian. Four Afghanis who had been also kidnapped have been released.

Foreign ministry yet to comment on unconfirmed report

The German foreign ministry meanwhile said it was working "in collaboration with all relevant sources and with the Afghan authorities for clarification of the circumstances."

Foreign Secretary Frank-Walter Steinmeier told reporters that at the time the foreign ministry only knows that the situation concerns "hostages of different nationality."

The Afghan authorities said that they could not confirm the abduction, saying they had no information about kidnapped foreigners in the Maiwand region near Kandahar where the Taliban claimed the abduction took place.

Germany has some 2,500 soldiers in Afghanistan as part of the International Security Assistance Force (ISAF). They are stationed in Kabul, Kundus, Faizabad and Masir-i-Sharif.