There were indications that the blast could have been a suicide bomb attack, but the exact cause has yet to be determined, the military spokesman told German press agency DPA.

The soldiers have already been discharged from hospital, the German military said in Afghanistan. But it remained unclear whether the incident was a targeted attack as it could also have been an anti-tank mine, sources added.

The attack follows a similar one in July in which three senior German police officers were killed when their vehicles were hit by a roadside bomb on the eastern outskirts of Kabul. In May, three Bundeswehr soldiers were killed and two others wounded when a bomb went off in a crowded bazaar in Kabul. Twenty-four German soldiers have lost their lives in Afghanistan since 2002.

In a separate incident, one soldier serving in NATO-led international forces was killed and two wounded in an explosion in southern Afghanistan while several militants were killed after they attacked foreign soldiers, officials said Friday.

Rise in attacks on coalition forces all over Afghanistan

The soldier killed in the blast died Thursday, a statement from the NATO-led International Security Assistance Force (ISAF) said, without revealing the nationality of the soldier, details of the explosion or a more precise place or time of the incident.

US, British, Dutch and Canadian soldiers dominate the foreign forces based in Afghanistan's southern provinces. Germany has 3,000 troops in the north of Afghanistan as part of the ISAF's reconstruction mission as well as six Tornado reconnaissance jets and their crews.

Afghan and US-led coalition forces also killed "several militants" Friday in the south-eastern province of Paktika, a coalition official said.

A military statement released from the US base at Bagram outside Kabul said Afghan and coalition forces were on a search operation in Waza Khawa district and came under attack by Taliban militants.

Missions against the Taliban continue

The operation was launched on the basis of "credible intelligence" suggesting that Taliban fighters were hiding in the area, the statement said.

"While searching a compound, Taliban fighters opened fire and threw grenades on Afghan and coalition forces," which fought back and killed a number of Taliban fighters, spokesman Major Chris Belcher said.

"Several coalition force members were wounded as a result of heavy fighting," a coalition statement said.

The statement said Afghan and coalition forces responded with small-arms fire and precision-guided munitions, destroying the building housing the militants while some damage occurred to other buildings on the compound.

According to initial assessment, several adult males, an adult female, and one child died and two children were wounded in the building housing the militants, the military report said.