The son of the Netherlands' new military chief was among two Dutch Nato soldiers slain on Friday by a roadside bomb in southern Afghanistan, a day after a suicide blast killed 25 Afghans.
Two other soldiers were injured in the incident that killed Dennis van Uhm, the son of General Peter van Uhm, who was named top commander of the Dutch armed forces on Thursday.
The hardline Taliban movement had threatened to step up attacks against Dutch forces in Afghanistan if a far-right Dutch lawmaker broadcast his anti-Islam film, which was aired last month.
"We remain determined to do what is expected of us -- united," Defence Minister Eimert van Middelkoop said at a press conference in The Hague.
The four soldiers were returning from a reconnaissance mission when the bomb blast hit their vehicle in the troubled southern province of Uruzgan, Dutch defence ministry spokesman General Freek Meulman said.
The two killed were 23 and 22 years old, said Meulman. Among the two injured, aged 20 and 25, one is in critical condition while the other is stable.
Uruzgan police chief Juma Gul Hemat said the incident occurred near Tirin Kot, the provincial capital. "It was a roadside bomb blast which hit the Dutch soldiers. Two soldiers were killed," he told AFP.
More than 1,600 Dutch soldiers are currently deployed in Afghanistan as part of the Nato-led International Security Assistance Force (Isaf), which is fighting a stepped-up insurgency by the Taliban.
The Dutch government decided in November to extend the mission until late 2010.
Sixteen Dutch soldiers have been killed in the country, either in accidents or combat.
The latest casualties brought to 44 the number of foreign soldiers killed in Afghanistan this year. The violence took the lives of nearly 220 foreign soldiers last year.
Three Afghan civilians died in another roadside bomb blast near the capital Kabul on Friday, police said.
The men were killed and another wounded when their vehicle hit a bomb laid on a road frequently used by Afghan and international forces in Logar province, provincial police chief Ghulam Mustafa told AFP.
He blamed the attack on Taliban-linked militants.
The attacks followed a suicide bomb blast in the southwestern province of Nimroz on Thursday evening that killed 25 people including two senior police officials.
A spokesman for the Taliban said the group could not immediately claim responsibility for the Nimroz attack.
"We can't claim that suicide attack yet. Our Mujahedeen on the ground have not yet reported having carried out such an attack on Thursday," rebel spokesman Yousuf Ahmadi told AFP by telephone.
Thursday's attack in the provincial capital Zaranj took place in a crowded marketplace near the city's mosque. Dozens of worshippers had left the mosque after evening prayers.