Kabul - A NATO soldier was killed Wednesday in an attack in the southern region of Afghanistan, where a roadside bomb explosion wounded six civilians, officials said.

The soldier, whose nationality was not revealed by the alliance, was killed in a "hostile incident" in the southern region, the International Security Assistance Force said in a statement.

The southern region is the main hub for Taliban insurgents in the country. One Dutch and one Romanian soldier were killed in two separate attacks in the same southern region in the past two days.

Six civilians were wounded in a roadside bomb blast in Daman district of southern Kandahar province on Wednesday, Zelmai Ayoubi, spokesman for the provincial governor, said.

One civilian vehicle was hit by the bomb on a road near a NATO military base in the district, he said, adding that the second car driving behind could not brake and rammed into the first car.

He said the wounded civilians, two of them in critical condition, were evacuated to a local hospital for treatment.

In another incident, suspected militants fired a rocket at a German base in the northern province of Kunduz on Tuesday, but there was no report of injuries, the German military said on its website.

There are more than 70,000 international troops under the commands of NATO and US-led coalition forces in Afghanistan. Some 21,000 additional US soldiers and military trainers are expected to arrive in Afghanistan by mid-summer.

Another 5,000 soldiers from other contributing countries are also expected to arrive before the August presidential election. (dpa)