Isis fighters in Syria were shown unpacking hand grenades from boxes stamped DM41, which experts say is the classification of an older hand grenade type used by the Bundeswehr, the German Army.
A Bundeswehr spokesman declined to comment on operations to supply Kurdish forces fighting Isis in northern Iraq, where the terrorist group is believed to have intercepted western-supplied weapons.
But other military officials told the news agency dpa that only new type DM51 hand grenades could have been among weapons delivered to the Kurdish defenders of the northern city of Kobane a month ago.
Confusion over the origin of the hand grenades deepened with a Pentagon admission that a US airdrop of arms to the city's defenders could have been snatched by Isis.
The hand grenade video appeared following a US airdrop of 28 crates of weapons and supplies to Kobane earlier this week. One crate went astray when landing. Despite efforts to destroy it from the air, the contents may have survived, officials said.
They were unable to comment whether German items were among the delivery. Since September 5, Germany has supplied 5,100 hand grenades among 600 tons of arms, vehicles and equipment to Kurdish forces in Iraq,
Repercussions of the conflict in Syria and Iraq have affected Germany in various ways in recent months.
Hundreds of volunteers have travelled to the region to fight for Isis, while Isis fighters originating in Germany have threatened the life of Chancellor Angela Merkel. Funds and equipment were also supplied to groups fighting in the region by sympathizers in Germany.
Four men were arrested on Monday for allegedly supplying thousands of winter boots and jackets to terrorist groups.
Related raids were carried out in seven states, including Baden-Württemberg, Hamburg, Hesse, Rhineland-Palatinate, Saxony, Schleswig-Holstein, as well as North Rhine-Westphalia.
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