Hamish Macdonald, Al Jazeera's correspondent in Kabul, said: "There has been a spike in crime here in recent years ... and there has been pressure politically on the government to carry out stricter punishments."
"The death penalty is legal here and under sharia law it is acceptable," he said.
But the UN Mission in Afghanistan expressed disappointment at the executions, saying it had been a "staunch supporter" of a moratorium on the death penalty that Hamid Karzai, the Afghan president, appeared to have observed over the past years.
The last known execution by Karzai's post-Taliban government was in April 2004 when Abdullah Shah, a former military commander convicted of murder, was killed with a single bullet after being convicted for a spate of murders.
Tom Koenigs, a UN special representative, urged the country to "work towards attaining the highest human rights standards and ensuring that the due process of law and the rights of all citizens are respected".
"Lesson to others"
RTA said the executions were carried out in accordance with the sharia (Islamic law) and as a "lesson to others" who are "taking advantage of the security conditions of the country".
Among those executed was Reza Khan, who was convicted of killing three foreign journalists travelling to Kabul from Pakistan in 2001 to cover the fall of the Taliban government.
A man identified as Farhad was executed for murder and for the May 2005 abduction of Clementina Cantoni, an Italian aid worker, according to RTA.
Cantoni, who had been working with Care International, was snatched from her car at gunpoint in the centre of Kabul on May 16 and held for 24 days.
Timur Shah, the leader of the gang involved in her abduction, had also been sentenced to death but was not among the group executed.
One source said that Shah had escaped just before he was due to have been shot.
Taliban criticises executions
A statement, said to be from the Taliban, accused the authorities of killing only men who could not afford bribes to save their lives.
It also criticised the government for carrying out executions during the holy month of Ramadan.
Between 1996 to 2001, when the Taliban ruled Afghanistan, the religious group frequently carried out executions in public, including beheadings and shooting people in the head.
Crime has soared in Afghanistan since the toppling of the Taliban government in 2002, despite the presence of tens of thousands of international troops in the country.