"This is a tragic case, but we must assume that it will be repeated," GdP chairman Konrad Freiberg said in the daily Hannoversche Allgemeine Zeitung. "We are in the sights of the Taliban and other Islamist terrorist organizations."

Three German police officers responsible for protecting the German ambassador to Afghanistan died and a fourth was injured when their vehicles were blown up on a road to the east of Kabul on Wednesday.

Freiberg said terrorists were aiming to influence Germany's decision on whether to renew its deployment of German military and police in Afghanistan, which parliament will consider in the coming months.

Tanks for police?

Freiberg disagreed with proposals from the rival German police union, the DPolG, to outfit police in Afghanistan with military equipment. DPolG chief Wolfgang Speck had called for them to be provided with tanks, armored vehicles and equipment to jam remote signals that could detonate bombs.

"We do not want the police to be militarized," Freiberg said. But he said security arrangements for the police should be reviewed.

The calls for reviewing the measures taken to protect German troops and officials in Afghanistan were backed up by politicians from Merkel's Christian Democratic party and the opposition Green party.

There was a broad consensus not to allow such attacks to influence Germany's commitment to Afghanistan, Deputy Foreign Minister Gernot Erler, a Social Democrat, said of the bombing.

Germans not necessarily targeted

Contrary to initial reports from the Afghan police, the slain Germans' all-terrain vehicles were not marked with any national emblems, such as flags, ARD television said. Thus, it was unlikely the attacks were intended to hit Germans in particular.

The four had been driving to a training session when the bomb exploded. The road they took to reach the shooting range, and the range itself, were known as places frequently used by foreign security services.

Police authorities were preparing to hold a memorial service for the three men in Berlin's central cathedral, the Dom, on Saturday. All of them were between the ages of 30 and 40.

Merkel's former bodyguard among those killed

Bild newspaper reported Thursday that one of the victims had been a long-serving bodyguard to Chancellor Angela Merkel. The 31-year-old officer from Nuremberg had planned to return to duties guarding Merkel in December after a stint in the German embassy in Kabul, the paper wrote.

The officers, all of whom worked as security staff for the embassy, were the first German police to die in Afghanistan since the beginning of Germany's mandate there. The deaths brought to 24 the number of Germans who have been killed in Afghanistan since German troops joined the NATO-led International Security Assisstance Force (ISAF) in 2001.

Some 3,000 German troops are engaged in reconstruction in northern Afghanistan as part of the ISAF.

German politicians have vowed to continue with their peacekeeping mission in Afghanistan despite the latest attacks.

German Defense Minister Franz Josef Jung said on Thursday, the Taliban were trying to sway political debate by "underhanded, one-sided attacks." If we give in now, the terrorists will acheive their goal, he added.

The latest German casualties have however raised deeper questions of Germany's involvement in Afghanistan and exposed strains within the governing coalition of Chancellor Merkel.