German authorities may soon release three suspects who were detained following a blast near the AfD's local office in Döbeln, officials said on Friday.

The men, local Germans aged 29, 32, and 50, are suspected of detonating an "unknown substance" in the street on Thursday evening.

The explosion damaged the door and windows of the AfD office and set fire to promotional materials inside, prompting firefighters to deploy to the scene. Nearby cars were reportedly also damaged. No injuries were reported.

On Friday, prosecutors said they suspected the three men were behind the attack, but added that they would not request their detention because there was insufficient grounds to do so.

"The attack against the AfD office in Döbeln is extraordinary given that the explosion meant accepting that people could be harmed," the state police said. A task force for investigating extremism and terrorism, it added, was probing Thursday's incident.

Police said there had been a series of attacks against AfD offices in the eastern state of Saxony in recent weeks, but added that most of them were limited to vandalism.

An AFD office in Saxony-Anhalt was vandalized with red paint in November

Attacks 'helps the AfD'

Saxony's Interior Minister Roland Wöller said the state would not tolerate such attacks and pledged a severe response.

"We are dealing with a completely new level of violence against politicians," he said.

Martin Dulig, Saxony's deputy prime minister and a member of the center-left Social Democratic Party (SPD), condemned the attack Friday morning on Twitter.

"There's no justification for the attack on the AfD office in Döbeln," he wrote. "Violence is not a means of democracy. The AfD must be fought politically and not with explosives. This attack helps the AfD and hurts democracy."

dj,dv/sms (AFP, dpa, EPD, Reuters)

Each evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.