Ronald Pofalla, the secretary-general of German Chancellor Angela Merkel's conservatives, said the attack demonstrated the West can't leave Afghanistan.

“Germany does a very important job to help stabilize the situation on the ground," he said in a statement Wednesday. "The Afghanistan mission is right and important. We must not retreat because of the terrorism of the Taliban.”

The three officers of Germany's Federal Criminal Office, deployed to Afghanistan to help secure the German Embassy in Kabul, died Monday when a landmine was ignited via remote control next to their vehicle. A fourth man survived and was flown to a nearby German military hospital in Camp Warehouse, Spiegel Online said. French bomb squads and U.S. soldiers afterward secured the scene of the attack.

The bombing is the latest in a series that has hit Germans in Afghanistan; in June a German military convoy was attacked, but no one was injured.

In May a suicide bomber blew himself up in a busy market square in Kunduz, killing three German soldiers and five Afghan civilians. More than 20 people were injured.

It is also nearly a month since a German engineer and his colleague were kidnapped in Afghanistan; one man was shot after he collapsed in captivity; the other recently begged for his life over telephone.

Observers say Germany has become a terror target because the Taliban wants to force the roughly 3,000 German troops out of the country. Public support for the contribution to the NATO-led stability force ISAF and the U.S.-led anti-terror mission OEF is low in Germany, and a parliamentary decision over the missions' continuation is due this fall.