The Kosovo anti-terrorism authorities have accused the three Germans of being involved in planting the bomb, and arrested the trio last week.
An initial statement from Pristina said, “The Germans are neither diplomats, policemen, soldiers, nor experts with international identification.”
But it has emerged, according to a report in this weekend's Der Spiegel, that the men are all agents in the Bundesnachrichtendienst, the German overseas secret service.
They say they had nothing to do with the bomb, but had simply inspected the building from where it was thrown. One was spotted as he went into the building, but says he wanted to take a photograph of the damaged office. He and his two colleagues were arrested on Wednesday.
Their unregistered presence in Kosovo has damaged diplomatic relations, the magazine says. Generally agents are accredited with the state in which they are working, in order that they can be covered by diplomatic immunity.
This was not done in this case, the magazine says, leaving the men open to potential charges of spying.