German officials say they've taken security measures at a popular German magazine and for members of a small far-right party after a known terrorist called for them to be attacked in a video online.

The video surfaced May 18 on YouTube following street clashes between an ultraconservative Muslim group and the far-right Pro NRW party in Bonn. The Salafist protesters were upset by Pro NRW signs showing unfavorable cartoons depicting Islam's Prophet Muhammad.

In it, Bonn-born Yassin Chouka, who is believed to be with the Islamic Movement of Uzbekistan in the Afghanistan-Pakistan border region, calls for Muslims to kill Pro NRW members.

He also calls for the murder of Der Spiegel employees for printing pictures showing the cartoons.

Security officials said Tuesday they worry the message could inspire lone-wolf attacks.