Bavarian interior minister Joachim Herrmann defended the suggested change to the law at a meeting of state and federal interior ministers in Dresden.
“It would only be possible in extremely exceptional cases,” said the conservative Christian Social Union (CSU) politician, pointing out several cases in which minors had been brainwashed into carrying out violence, or had radicalized themselves in recent years.
Currently spy agencies are not allowed to save any data on anyone under the age of 18.
According to Herrmann, it is “divorced from reality” to argue that investigators should look the other way when they learn about a radicalized minor.
Roger Lewentz, the Social Democrat interior minister in Rhineland-Palatinate, described the Bavarian proposal as “unthinkable.”
"That we would send the intelligence agencies to spy on juveniles - that isn't going to happen," Lewentz said.
"That is not only not possible, but it goes against everything we stand for politically."
There have been several cases of radicalized minors attempting commit violent crimes against the public in recent years.
Earlier in June, 18-year-old Saleh S. was sentenced to eight years in youth detention after he attempted to set fire to a shopping centre in Hanover in 2016.
Saleh S. was 17 at the time of the crime, and admitted to the court that he wanted to kill as many people as possible. No one was injured or killed in the incident.
Saleh S. is the older brother of 16-year-old Safia S., who was convicted of attempted murder in January and sentenced to six years in jail.
The teenage girl stabbed and severely wounded a 34-year-old police officer, reportedly as ordered by Isis, though the terrorist group did not claim the attack.
Meanwhile in April, a Syrian teenager was convicted of planning a bomb attack on behalf of the Isis terror group and sentenced to two years' juvenile detention.