A roadside bomb has killed 10 workers as they were on their way to clean streams in southern Afghanistan.
Separately, an Afghan deputy intelligence chief escaped an attempted suicide bombing claimed by the Taliban in the capital.
The attacks came as Nato's secretary general said that plans to hand over control of seven provinces to Afghan soldiers in July remained on course, despite new bombings and assaults by insurgents who recently started their spring offensive.
Nato also acknowledged that soldiers shot dead an Afghan holding a torch during a raid, something that could add to the growing anti-foreigner sentiment in Afghanistan after nearly a decade of war.
The roadside bomb tore through a truck carrying the workers through Kandahar province, said Dr. Qayoum Pakhla, the director of Kandahar Hospital.
"I could see people calling for help and crying," said one of the survivors. "I saw some of my friends' dead bodies. I was helpless at that moment."
There was no immediate claim of responsibility for the attack in Kandahar, which has seen a rise in incidents in recent days as Taliban fighters try to retake territory lost in the past year.
Meanwhile, Ahmad Ziad, a deputy chief at the National Directorate for Security, escaped injury in an attempted suicide bombing that targeted his convoy as he was travelling to work.
His bodyguards opened fire on a suspicious vehicle heading toward his convoy, wounding the driver and stopping the speeding vehicle which was filled with explosives.
The growing number of attacks come as Nato and the United States hope to begin relinquishing control of security to the Afghan military through the end of 2014. President Barack Obama has said the United States, with about 100,000 troops on the ground, will begin a gradual drawdown in July - with the number to be determined by the situation at the time.